Whoa big topic!
I work with a large scale breeder and can answer some questions.
1st make a few descisions to narrow thwe field.
1)Captive bred or wild caught?
CB is more eco-friendly, and specemins are usually much heartier, plus CB tarantulas are usually on northern hemisphere breeding cycle.
WC is much cheaper.
2)Adult or spiderling?
adults are much more expensive
spiderlings are much cheaper but somewhat fragile
also many species are not available as adults.
3)handleable or display only?
most old world species are agressive and can have more potent venom
most new world species are more docile, less potent venom, but have urticating hairs which can itch burn and cause allergic or eye problems
Well I really could go on for hours, but the sopranos is gonna be on soon.
Check out avicularia versicolor (antille's pink toe).
I currently have 13 of them.
They are beautiful and easy to handle, fairly easy to keep, but need high humidity.
Post some specific questions I'll try to help.