I've seen a few recipes using sour cream instead of mayonnaise, that's probably nice enough.
As an aside, here is my homemade mayonnaise recipe that is really wonderful and easy to make.
1 whole large egg
1 1/2 tsp mustard (smooth)
1/2 cup olive oil
1/2 cup vegetable oil
1 tbsp red wine vinegar
salt and pepper to taste
I use my blender to make this and you can't go wrong, no problem with separating or anything like that. It looks like this:
I use the whisk attachment with the cup.
So, just put the whole egg into the cup together with the mustard and mix them up with the tsp a little.
then add a little olive oil and turn your whisk on in there.
when that's blended up, start trickling the olive oil in gradually, giving the mix time to blend, if it starts to get all oily inside then stop adding the oil, blend up and then continue. The mayonnaise should start to thicken up. Keep going till all the oil is in and you have a smooth, thick, yellow mayonnaise. After you can add the vegetable oil to give the mayonnaise a lighter flavour. When you've added all the oils, then stick your finger in it, the mayo should be thick and consistent and yellow. Add some salt and pepper and the vinegar and whisk again. Don't overwhisk it all or you'll end up with mayonnaise mousse instead of a creamy consistency.
Taste it to check seasoning and voilá - all natural yummy mayo. This makes a big quantity so just add less oil if you don't want so much mayo.
I use the whole egg as opposed to the egg yolk only because it makes the mayo much lighter and fluffy.
optionally you can use only olive oil to make it less unhealthy but it makes a much stronger taste, and not quite like the mayonaise you're probably accustomed to.