Where is this house located?

How thick is the crushed rock and what size (fines, 1 inch minus...?), and how thick is the sand layer on top?

If it's fairly thin, it can be tilled in and amended with compost. If it's thick, it may have to be removed.

Your location makes a difference in what you can grow in what kind of soil.

I'm not sure how far down my sand goes, I have dug 4 to 6 foot deep holes and have not found anything but sand. Adding organic matter to this sand has turned it into something that will grow strong and healthy plants that produce quite well and with few insect pest problems.
There are no quick fixes for what you have to work with, although sod can coceal it.

Since you're talking about selling the house I would suggest talking to a few realtors about what would work well for sale. An experienced realtor with local market knowledge should be able to tell you what would be a positive or negative issue for sale.

At this point if the base was well prepared, and done properly, your best, fastest option may be to complete the artificial turf installation. They are becoming increasingly popular options for homeowners who don't want the maintenance hassle of natural turf.

If AT installation isn't a viable option, then it's recover and plant. Typical residential AT installations in place of natural turf are done over a base of a small crushed aggregate filled with fines. The usual depth is 2-6 inches, depending upon your climate (arid climates need less than wet climates). It's all about drainage in heavy rains. Before you plant anything you need to find out how the base was constructed, how deep it is, and what materials were used. If crushed limestone was used you will be facing alkaline conditions unless you remove the base prep and start over. Next is to consider plants that would grow in your climate in that kind of soil. There are many variables, and since you haven't mentioned where this is located it's very difficult for anyone to suggest what might work. You probably should consult local expertise, like an experienced landscape designer for good, viable options.