Well I am no expert, let me get that out of the way. I am also looking to purchase a JTAG. As I have discovered you first have to decide if you want a JTAG or a RGH (Reset Glitch Hack) The main differences are: A: RGH Costs more typically, B:RGH Can run dual nand ( you basically run an offline hacked xbox, and then you can switch to your normal xbl xbox but its all in 1 console.) C: RGH's boot slower and are constantly trying to be patched by microsoft. D: RGH's take a longer time to boot up due to how they work (they have to reset the motherboard everytime, thus the title "reset glitch hack") E: The dashboard on RGH is a more current dashboard vs the jtag old one. I am currently debating between the two. I already own a normal xbox 360 so I have no need for dual nand, so I am leaning toward a JTAG. Once you have decided that the JTAGS rank up as follows xenon, Zephyr, Falcon, Jasper. Jasper being the newest version of the xbox (least likely to break) So if you are going for length I would personally suggest the Jasper. Or If you are considering buying an RGH, (This is the main reason I may still get an RGH) You can go 1 higher and get a slim rgh (newest of the xbox's) This will obviously last you the longest. Also do note that the higher you go on that tree of modded consoles the more pricey you get. Then your final question, "Where would I buy one?" To which I would answer: At first I had the exact same question then I looked under the jtag help topic and saw : xbox marketplace. Forums/f=187/xbox-360-marketplace.html
All of the sticky threads should be trusted sellers that you can buy your modded console off of. First look in the title and find one with your location (it will say US or UK). Then click on them, browse around those and find the best price. Don't forget to factor in that you need to buy AV cables, power brick, HDD (recomended that you get a preloaded one from them which will save you a ton of work) and most modded consoles automaticly come with a flashed drive (can play pirated games essentially) but, if it doesnt then you may want to invest in one. Also If you want the dual nand feature on your RGH remember to factor that in too ( RGHS dont automatically come with dual nand usually) This can be added for around $100. Anyway do your research and compare total prices so you don't get ripped off! Anyway hope this helped (took me like 30 mins to write so I hope it did! Anyway +rep would be appreciated Have a nice day!