I find , my local Walmart to be almost double if not triple the prices of Amazon, for what I'm buying and the area. I have never had a bad card from Amazon though I'm sure someone her will say they have... I use a 32 Gb class 4 cart (less than $15.- 19 USD new right now Amazon) and have a mix of Nes, Snes, DS, GBC, & GB, & GBA, and free license real homebrew, over 100 full readme guides, several DPG videos, a seperate browser, email etc... totalling 707 (games alone) in all. G-d I love this card...best investment evaaar. It all works flaw-lessly. Over 450 are DS games, untrimmed, uncompressed. I suppose I could fit more on but these are all ones I actually use, so what's the point.
(I am actively working on owning hard physical originals, w/ labels and paper instructions of each and every one. I'm 3/4 of the way there now, just for collecting purposes. My daughter will get an awesome collection someday.
I figure I have enough to last until the 'Pip-Boy 4-D wrist-mounted Holo-emitter' is released by Nuke-a-tendo
I seldom take the card in and out and have the same cart for four years now. I believe the less I take it in and out of the slot, the less likely springs are to break or data degredation/corruption from writing, deleting elc.. or from copying copies, or contact tines to gum up or wear out. I keep a smaller 4gb for testing games on and another card for same purpose.