Start cheap! The first saw I modded was an old edition 346xp, I never could get it to run right, even before modding and after much frustration I got drunk and tore into my Husky 350. It runs like a striped ass ape so I sold the 346!
Seriously, find a used half trashed saw, all the information you need is on this site, and more, just research a bit, then open it up. You don't need a machine shop, a dremel or a foredom are great starting points unil you want to build racing saws. But first and foremost just have some fun with it and see what works and doesn't, then figure out why.
I personaly think the Huskies are easier to take apart and work on, but if you get a cheap 026 go for it! The Dolmars, unless burnt up, are going to be costly because they are so new to the market. The Echo's are just a flat out PITA to work on, but thats my honest opinion.