Any question answered...

Namrick.

Where can I buy 10 of each of the following in an economical fashion?

Depends...

What bolt head? What material? Do you have a local fastener shop?
In A2 stainless or 8.8BZP with hex heads, it's going to be about £3 from your local shop, but nearly £8 with shipping from either my preferred online supplier or Dan's

Screwfix?

as tester says depends on what bolts you want, but you can get 100 stainless nuts for £3.09 and 100 washers for anywhere from 49p, depending on size...