I am not disagreeing but to offer a different take on the situation...
A gecko from a reputable breeder (such as those listed by GreggMM) while an excellent choice is not always economically feasible. Many breeders are specializing in specific high end morphs etc. Geckos are selling for upwards of $1000. Of course some can be had for less ($150 - $200) range but that is a lot for a leo you want as a pet. I also don't think it is fair to automatically disqualify the classifieds. There are some very good small breeders out there without the name recognition of say Urban Gecko or H.I.S.S, who produce very healthy geckos which make great pets. They often list their animals in the classifieds. My wife's favorite animal of ours is a normal leo we got for $35 from our local reptile store. It is technically a pet shop, but they breed their own stock or sell those of local breeders. He is now 5 years old and is very healthy. While I wouldn't recommend one of the big chain stores getting one from a small breeder can be a very economical way to get a healthy pet quality leo.
Jon
Of course I do not mean to imply that the smaller, lesser known breeders are not "reputable." I merely mean they are not well known and therefore may not have a "reputation" like some of the breeders mentioned.
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2.0 Leos (Spot - Normal but oh, so sexy; Jessie - hypotang)
3.2.4 Fattails (Henri, Suwannee, Valencio, Dixie, Isis, Zipper, Pheonix, Hissy, and Snickerdoodle)
0.0.1 redfoot tortoise (Sherman)
0.0.1 sulcatta tortoise (Tinacious aka Tiny)
1.1 Dogs (Zubin and Brenda)
0.1 cat (Mimi)