Hey H. S:
I hate to tell you this but I think you are SOL! Ah - the art of the Mother-In-Law games:)
The problem is...if your Mother-In-Law is like mine - she has helped you out in the past either with babysitting, loaning or giving you money, or even just storing your stuff at her house. In her mind it was probably pay back time.
It always seems things are worse when we don't discuss them and then it just builds and builds...you could always just sit down and talk to her - but that's never worked for me, so I play the game.
When my husband and I bought our first house, our in-laws had to co-sign for our house. Just prior to signing the loan...they bought a new car not knowing that their purchases then effected our loan. We had to move one of their credit cards to my credit card (since I was too in debt to be on the loan) so that they would be approved with co-signing it. After we bought our house and several months later they were OK with moving it back over to their credit card - but my FIL was furious that I requested the interest too which was a few hundred dollars.
Looking back that was probably pretty tacky of me. They had given us money for the wedding and stuff for our new house as well as babysat our kids for free for awhile. So with this being said- I think you might have to let it go.
But - Here's one last ditch effort at the game...Once you do buy your new home (and it might actually come with a dishwasher) you might suggest your need for a dishwasher to your MIL reminding her that you had a perfect dishwasher at one time that is now in HER house - but it would be difficult to afford another one like that at that time. I doubt she will rip out her dishwasher...but you may see some cash.
We just have to chalk these up to a lesson learned.
J. G