explorer22,
I had the same questions and concerns you did. I read everything I could get my hands on, talked with people (online) about their experiences. In the end I am very pleased with my decision. I started out thinking I was going to go the route of the SHARK HD3. But after doing more reading and learning that it was made from plastic I rethought that... In the end I went with a Probotix Asteroid and boy I am glad I did! Well made machine, all aluminum and steel, made in the USA. LEN was very helpful! After having the machine for months I am very pleased... I am starting to do some pretty good work and have really started feeling like I could make the machine act the way I want... So I will break down for you what I learned in the months of reading I had...
1. CNC is not cheap. However, It can be a really big boost to your woodshop if you are selling pieces. If you are just doing "home projects" a CNC can be a great addition but you need NOT spend 10,15 or 20,000+ to get great results.
2. Buy your 2nd machine first. I am glad I did this. The shark may be a good machine, but I wanted something all metal and made in the USA. Really you need some insight as to what you want to do with the machine. Is this for a home user just cranking out a few things here and there or is this for more production type aspects. (It makes a difference)
3. Buy something with great support both in the forums AND from the company. Probotix has been very helpful for me... so I am pleased with my choice.
4. Work area, consider what you will be making, if you are making furniture and larger pieces you will want something larger than say the Shopbot Desktop (A fine machine I hear) but the bed size for me, was way too small.
5. Software: There are 2 types, Controller and Design. CONTROLLER: I had work very basic functions in Linux and the LinuxCNC software was VERY easy to master. Do not be worried about Linux operation, I have found the Linux software to be a great performer... it just keeps running and running, unlike my experiences with Windows which has lots of maintenance issues. I too was a bit afraid of the entire Linux thing but it has turned out awesome for me! DESIGN: There can be no question in my mind after all my readying. Vertric is the WAY TO GO! I started off with VCarve Pro Ver 8 and I am glad I did. I REALLY WANTED Aspire but the $2,000 price tag was more than I could do initially... learning Vcarve will give you all the things you need to get started and will help you get ready for ASPIRE when you can afford it. My plan is to sell a few pieces and upgrade to Aspire later. With Vectric you can upgrade and they will give you a huge credit towards Aspire. I believe VCarve Pro is $699 and when you upgrade they will give you $599 towards to cost of Aspire. So for $100 I consider that pretty cheap learning! The fact is most Newbies will not be ready for Aspire out of the shoot. 3D work is Very different that 2 and 2.5 D work. My advice, master VCarve, then upgrade if you need to.
6. Other costs to factor in:
a. Tooling - I spent $250 to get the basics from US Router Tools, and I am pleased. Make sure you get the following: Tred Leveler (TO level any wood projects) 60Degree VBIT, 90Degree VBIT, 1/8 Endmill, and a 1/4" Endmill. That will get you going for sure. I order a few other bits to get to $250 but I have yet to use them...
b. Table - Make sure you build or have a very solid table. I made one for my Asteroid and I am so happy with it.
c. Dust Collection: But the Dustboot and connect your Shopvac to it. CNC makes a mountain of dust and you do not want to break any of that in. PLUS is makes a huge pile of sawdust all over your table and such.

d. USB Sticks - Buy a few as you will use them (most likely) to transfer files from your design computer to your CNC computer.
e. Computer - Probotix CNCs come with a computer too... which was huge for me as some of the brands I was shopping did NOT include a computer. Everything is pre-loaded from Probotix and tested... so you are ready to go out of the box!
f. Design Computer - You will need something to load your design software on... I happen to have a Mac running Parallels and I found that to be perfect!
G. Router - You will need to buy a router too. I went with the Bosch 1217 and Its been great!
Last but not least - TEST STOCK.... you will need lots of wood to practice! I found some cheap MDF pieces at Home Depot ($1.99) and I have been using them. But in the end you will need lots of wood, Oak, Maple, pine, etc.. so I would factor in $400-500 worth of test / final wood in your costs to get started.
In the end I spent about $6500, soup to nuts, and I am pleased. People marvel at the things I am making now which will (I hope) translate to some real $$ so I can support my CNC addiction
I have seen some used Probotix equipment up for sale at a good price ... so if $4-6K is more than you can do (and TRUST ME I UNDERSTAND!) a probity is good shape is a great choice.
I know this was long but I wanted to share what I have learned, others may disagree with some of my points and that is ok too, I am still new at this myself. BUT I can tell you that CNC is great and I am loving every minute and I am very happy I went with the Probotix guys. In the future I might Upgrade to a Camaster 3 (for size purposes if I start cranking out more production things, but for now, with my small shop the Probotix Asteroid is great. Give some consideration to the Meteor by Probotix is you want something a bit larger. 2 months or so in and I am still very pleased. Yesterday I made a sign for my daughter (See attached) its not perfect but it shows what you can do at a basic level

I also attached some inlay shots of the planet chest I made for my son's wedding. I center tree is Walnut inlay and the leaves are exotics, all done with the Probotix CNC.
Good Luck Explorer22! Looking forward dot hearing how you make out!
ProfL