@Darrell Jones
Darrell,
A lot of folks here have given you good advice--even if they might have been a bit harsh in some cases; but, hey, didn't we just have an international economic meltdown created by bad real estate investments, bad banking practices, etc., causing the nation, as a whole, to lose somewhere in the 5-10 trillion dollar range in accrued wealth?! It's no wonder some folks are touchy about this subject. Your best bet might be to go to the seller, hat in hand, and beg out of the contract. But let's explore a couple of other options--you still have time to get something done if you're willing to work hard, fast, and also be teachable/humble towards someone out there in your market area who can help you.
My first observation is that you seem to have a decent rapport already established with the seller, and the seller seems to be very motivated, as evidenced by the agreement to reduce the already agreed-upon price. The first rule in negotiating is don't stop talking; keep at it, 'no' doesn't mean the end, it simply tells you where boundaries or pitfalls lie. Second, you need to determine what makes a win-win scenario, and steer towards that--nothing else matters. Don't appear to be a wolf; be a sheepdog instead. Protect the seller's interest, as much as possible. Here are some ideas:
1) Find out what the seller needs--this really ought to be the first thing you do every time. Listen, ask questions, find out the why. Solve a problem for them. Maybe they simply need cash--would they be willing to refinance, take cash out, and let you take over the payments, with a little extra each month, same scenario as 2) above. Do they need credit help? Although not usually a good tactic, since you're already in a pickle, maybe you can help them with your credit to get the refi loan, for some consideraton on your deal's terms.
2) Do you have funding in place? If you're able to buy the house, why not hold onto it and rehab it yourself? Or rent it? You said you're getting it at better than 70% of market value. You need to find a partner or a private lender fast; sweeten the deal by giving them the lion's share of the potential profit for the benefit of saving the deal and also mentoring you.
3) Find out if the seller has to sell immediately, or can they provide more time, if you make it worth their while. One method might be to pay them an option to allow you to control the property for 1-3 years, and give you permission to sub-lease the property. Then you pay the seller enough each month to create a modest cashflow, but not too much to hurt your own cashflow (for example, if the mortgage payment is $1200, offer them $1250, plus $500 to $1000 per year for the option to control the property). Then market the property as a rent-to-own or lease-purchase option. Don't make the same mistake of not actually having the property under control, so that you'd be marketing something you don't have; but if the seller is willing, then you have a property you can market. (I don't know your numbers, so these are all just examples.) Place an ad like this: "Rent-to-own. 3BR/2BA, 1/2 ac, fenced yard, good schools, great neighborhood. Darrell, 212-123-4567."
Find out what the realistic rents are for like properties in that locale, because banks will insist that you charge a fair rate at a minimum, plus the additional amount over that for the eventual down payment from your lessee-buyer. Do some research on rent-to-own/lease-purchase options here on BP to determine how you want to set up your deal. But the basic idea is, ask for an option payment (for the option of renting-to-own) that would apply towards your buyer's down payment (some folks don't apply it; I always do); then your lessee-buyer pays an amount above fair market value each month, which overage is also applied to the down payment. So, if you had a $100,000 property, you might ask for $3000 for the option; if the rents in your area are $750/month for that property, then you might charge $1000/month, and $250 goes each month toward the down payment. You set the time period, and let the lessee-buyer know that these funds are not refundable if they do not exercise their option to buy, since they've taken your property off the market.
4) Inform the seller that you cannot make the purchase, but you'd be willing to help them find a renter and manage the property for them to ensure they get a good deal. (This is the least preferred, but it's a possibility.)
5) Ask the seller if they'd be willing to give you the option to purchase the house at said price in the next three to six months, and you'd be willing to pay them $5000 to $10,000 for that option, a non-refundable purchase, regardless of the outcome. Half of said option will go towards your down payment. Essentially, you're buying time so that you can go do the work needed to fix your deal by finding funds, buyers, a mentor, all of the things the previous posters excoriated you for not doing in the first place. You need to close your deal fast or make it worth the seller's while to let you control their property and take it off the market.