When they are little they seem to drop like flies (2" and below). There are 3 gold nuggets variants shown here:
http://www.monsterfishkeepers.com/forums/showthread.php?t=22382&highlight=L177
I would recommend a lot of oxygen flow in the tank, and make sure water conditions are as perfect as normal. I'd keep the pH around 6.5-7, slightly acidic beinig better in my experience. Make sure it has a few hides, i found this a must for this species (like many other plecos). Also i have found bogwood is very beneficial, and i know some people thing it is a necessitiy for this species, which I'd probably agree. They are pretty sensitive to temp so make sure its always at a constant and careful during water changes. Try feeding some veggies, I've had some that takes them, some that are not interested. Main bulk of their diet should consist of different worms, mysis, prawn, beefheart, shellfish etc, basically protein food. They are a grazer and sift through trying to find insect larvae, eggs, small crustaceans etc. I've never had a GN to refuse bloodworms

They are a pretty territorial fish especially when they get older.
$4.99 is a steal, but i'd be dubious if it is under 2-3", and check to see if it has any visible problems (ragged fins, off colours etc), but most importantly don't touch it if its got a sunken stomach (most common problem in these plecs). The hardest to catch is usually the healthiest

good luck with it.