sure. but the only sellable ones are pets that drop from mobs, quests, vendors or bag drops, like Mr Grubbs.
however, you can definitely run a search here for grinding profiles, using each pet by name, from a list like
https://theunderminejournal.com/category.php?category=companions&realm=H-Runetotem (change the server to yours)
you can also pick up the alliance/horde variants for some pets, but it's hard to trade them, you can of course, level up an alt on the opposing faction, and run the dailies for a month, per pet (probably 4+ months to collect them all)
a handful are grindable with evil drop rates, which can he handy for rep. or torture.
there's moderately rewarding collectors pets from places like darkmoon faire grinding, molten front bags (sigh) or argent tourney grinding, especially cross-faction tourney pets.
some grind profiles may need tweaking, but they're usually grind profiles for rares, so they don't change a lot.
there may be BoP pets coming in 5.1 from old raids, not sure if they will be tradeable, since they're mostly soloable, there's also the idea they will switch off the weekly lockouts at the same time, to let people farm for pets and transmog gear.