If we paid-ahead at the time of BX requests, we would not know which species were available. Sometimes I only receive one of two requested items. I would not want to burden our treasurer with refunds. If you use paypal then it is convenient to pay immediately upon receipt. If you use the personal reimbursement option then there is no per-payment fee, so it is ok to send just $4 at a time. I realize not everyone is comfortable with paypal. Thank you to Dell and Arnold for volunteering their time to make the BX run smoothly. - Gastil