I often have to make that tradeoff, too. The protocol I've settled on is to always buy the first one or two parts of a new type from Adafruit. This may also ha

I often have to make that tradeoff, too. The protocol I've settled on is to always buy the first one or two parts of a new type from Adafruit. This may also has the advantage of higher quality than no-name eBay sellers. That way, I know how a part is supposed to work, before trying cheaper sources. Then later, if I want a bunch of them for stock, or just messing around with (and maybe using up or breaking), I would buy from eBay. Also, if I'm placing an order from them (and already having to pay for shipping), I'm willing to pay a slight premium for any other things I might want to include at the same time. (This is the same tradeoff I make between buying from the more-expensive local hardware store that has fantastic people working there who have been in the trades and know everything versus Home Depot. Five 8 foot long 2x4's? Home Depot. Some specialized part that I want to get right one? The local store, even though it might be cheaper at the big-box place.)