It’s not how many you buy, it’s which ones you buy.

I just use a heat shrink tube of the right size. Ok, you can get a nice little kit with all sizes at a low cost from Lee Valley tools.

You can also buy them on abe.com or bookfinder.com very reasonably. Your local library may also have sales every couple of months.

Read a lot of books then you won’t worry about money anymore if you read the right ones.