It'll be a big chore collecting and issue receipts on that day.. u'll waste an hour to get this done and over with.. By then everyone lining up aledi sweating buckets. And it'll turn away last minute sign up.
I suggest u get ppl to deposit money using the Cash Deposit Machine (or cheque deposit machine). There are loads of Maybank branches all over, so not that bad..
Inform you of the payment via phone or PM (so that u can pre-prepare the receipt to be given out on event day)
Participant to keep and show the transaction slip on that day to get your receipt as proof of payment.
If participant can't produce transaction slip, then pay again loh..