Well, someone was nice enough to reach out to me and point out this thread. FHA, VA, or USDA financing are the most lenient loans for you to obtain with some credit issues. Have you viewed the HUD Appraisal Online (HomePath) to see what type of FHA Financing the home is eligible for? It would either say FHA 203b (standard FHA loan) or 203k (FHA Rehab Loan). The down payment would be as low as 3.5% of the purchase price on FHA. I lean toward FHA because it's more common (open to anyone to use) whereas VA requires an entitlement (length of military service/honorable discharge) and USDA restricts the property location/income (VA/USDA are 100% financing with no down payment though).
Most lenders cut off the credit score at either 580 or 620. They will use the middle score of all 3 scores. For example, if you have a 630, 620, and 500, they will use 620. If you have no personal derogatory credit in the last 12 months, and you pay some of your own bills reporting to credit for 12 months or more, there's a chance you'd be approved. You could document extenuating circumstances for derogatory credit on your report from your ex, and even better, if the divorce decree/separation agreement say those debts were her court ordered liability, you're pretty much good.
Usually, those auctions require a large non-refundable deposit be placed on the home at time of auction. (10% is common). It's very high risk for you to attempt to purchase a home needing repairs like this. There are very limited options for rehab loans, other than FHA 203k, for someone with low credit scores and derogatory credit. Another issue would be the value of the home vs the value of the land. If the land exceeds a certain % of the overall value, that could be problematic, but can usually be resolved by excluding the value of the excess land which sounds doable at the price it's at.
Government Agency loans rarely hit you hard on interest rate adjustments, so your rate would not be terrible, and your APR would be about the same as someone with a 740 credit score. Conventional loans are the opposite though.
I'm a Mortgage Underwriter for a bank and have been either Originating, Processing, or Underwriting mortgages since 1999. Discord me for more details. I'll help you out, buddy! Also, you do need to obtain a pre-approval in which you submit all of your income, assets, derogatory credit explanations, etc. to an Underwriter to review and either approve or decline your request. I'd be happy to look at credit karma or whatever self-pulled report to give you my guidance in more detail.