I have the book mentioned above and it is great. Loads of info and pics of the different localities, morphs, etc. Worth the $$ IMO.
I got my first carpet a few months ago and am enjoying him. I agree with the info above... Be choosy. I went to 3 shows looking for a carpet and only found one I liked at the last show I went to. Look for babies with clean color.. Most will brighten as they age, but if the "yellow" looks like mud as a baby, probably not a good investment.

The carpet I went with is a mix.. a jungle jag (High % IJ).. I wanted a classic high yellow jungle, but couldn't find any.

As for how well they ball up... Mine can get into tiny places. If you're familiar with the RBI plastic hides, my ~2.5' carpet was able to squeeze into a "small" and preferrred it to the medium for a long time.

They are a lot more active than BPs and also they take taming down. Mine is still not completely nip-free and this is after handling him quite a bit.