Nancy, folks have a tendency to "horriblize" situations such as "foundation work" way beyond the actual cost of repair! Plus it literally shakes their "foundation" in the subject property (sorry for the pun!). Unless you have some very strong bids for the work to be done, many buyers are going to still balk as working on foundations can have many hidden costs. Get the work DONE!! Do it with all neccessary permits and have it cleared by your local municipality or authorities that be.
I had a client redo his kitchen completely before putting it on the market. He'd lived their for 20 years and his wife nearly divorced him over it!! Here she cooked every day with some funky electric range with orange counter-tops, dark, walnut cabinets, fake brick backsplash, and here comes hubby putting in stainless steel appliances, granite counter-tops, custom flooring, backsplash, viking range, etc!! JUST TO SELL IT! This all had a happy ending. We sold it over asking price at a price they BOTH couldn't belive and he ended up delivering to her a brand new shinny BMW roadster as she walked out of their favorite restaurant!! Yes, pay-back is good!