SBA loans can cover financing for a business purchase and they can also cover the financing of working capital reserves. You'll still have to meet all of the qualification standards--both personal and business--before you can get a loan and you'll have to find a bank willing to lend. Though the latter has not been a problem until the past year or so, it is definitely an issue in today's very tight small business credit market.
The best approach is to contact the franchisor first to determine their experience with SBA loans and whether they are registered for expedited service with the SBA.
Second, contact your local bank(s) to determine if they are processing SBA loans.
Finally, find out if the seller is willing to carry paper for part or all of the purchase. Even if the interest rate is a bit higher, this approach may end up being easier and cheaper than going through the hassles and fees involved with an SBA loan.