I shop, barter, sell and buy to get what I need. It is a skill that would help many with their project and one that could allow them to build a reasonable electric car. Diggin for quarters in its self can be a wonderful hobby. Bust out your detector and start sweeping. Much of the time you will come up with pop tops but once and awhile you do find a little gem. Keep going because you never know when your hard work will pay off.
Don't get me wrong, building an electric car conversion is expensive but you can ease the pain in the pocket with frugal shopping whether you shop for new or used. Frankly I like new and get new when I can. Like the little JDL gauges with shunt and dc dc isolater from EVTV for $175 vs DIY for $107. That $70 bucks can go a long way towards buying one LiFePO4 Cell. That is a little shy of being able to buy one 60AH CALB cell. You know, I'd much rather save enough to help me afford just one more battery for my pack vs spending without care. A convenience store is NOT the place to do business in BULK. Its fine for the occasional slurpee or soda but not for all of your components.
The convenience store is all about spending the mighty buck. Not about saving the almighty buck. So go shop around. There are plenty of deals to be made but know what you need and price things out first.
Be smart when you shop. The convenience store is not always the smartest choice. Some times its the perfect choice, but most often not.