You could use virtual accounts for that, posting the received funds to your checking account and also to a virtual account that you eventually balance with the purchase (which would also have both real and virtual postings).
It's easy to confuse "virtual accounts" (imaginary accounts or subaccounts) with "virtual postings" (unbalanced postings), but remember these are different things with different uses. You can post to either kind of account with either kind of posting.
