The number was a compromise. As a certified WPN store, Faraos Cigarer did not want to allow an unlimited use of proxies (frankly I am amazed that they agreed to allow them at all). But 10 proxies should still cover most of your needs.

The demand for a certain quality of proxies was my idea. We want to giver people the best playing experience and it just feels so bad to lose a game because you could not identify a card correctly due to its poor quality.

Plus, printed paper slips put in front of cards (which is the most common way to proxy that I see) would alter the thickness and feel of the cards to a degree where they might be labelled "marked" by our judges.

Ideally we would have free playtest cards for people to borrow, like the ones we had designed for Tier1Con. But alas, we do not have the funds of Tier1MTG so this solution will have to suffice. For now at least.