One thing to think about is the gifting part. Right now, per the IRS, you can only receive $13,000 per person, per year without paying taxes on it. So if the aunt is going to gift the money to you all, not to the dealer directly, then she needs to divide up the amount. $12,500 to you, $12,500 to your husband. Any more than that and she'll be paying a large amount in gift tax (don't quote me but I've heard it's 30%). And... anything over $10,000 will be flagged by the bank and the Treasury Dept's money laundering dept will be looking in to the transaction (this is my husband's job)
http://www.irs.gov/businesses/small/article/0,,id=108139,00.html