Why get rid of it? You won't get anything so drive it until something major goes wrong, and then get something else. At least keep it as a second vehicle or something like that and use it for idk grocery shopping or for the kids to play in.

Also we as a forum are obliged to be respectful to any Astro like van thanks to @mountainmanjoe

Drive it till the wheels fall out and then get a different vehicle. They aren't worth much when you sell it. 

Yep, resale value is horrible. If it is the 4.3 V6 engine they are pretty bulletproof as long as you keep the oil changed regularly. And if your not dogging it surprising those transmissions hold up fairly well. The rest of the van will probably fall apart around you before either of those give you problems. Couple things to know on these.

1. The vacuum lines run across the intake manifold so occasionally your AC controls will die, blend door, vent selector. You’ll have to fix vacuum leaks. Use extra line and tie up away from intake. 
2. If its been awhile since you had a new serpentine belt, tensioner pulley or don’t remember if they have been done I would go ahead and plan on doing them. The tensioner on those years 4.3L have a tendency to not give any warning of failure. They just fail and your belt comes off. Won’t hurt anything if you pull over and stop driving, but can leave you unexpectedly stranded. 
3. Intake manifold gasket on some will fail and leak coolant into the intake valves, may look like a head gasket failure but way cheaper and worth it to fix. 
4. If intake gasket does go and you decide to fix it yourself be very careful to not let gasket material fall into the engine. My Mother-In-Law lost her engine when the tech was careless and didn’t pay attention to this. Day after she got it back the oil screen clogged while she was driving down the interstate, spun two bearings. I pulled the pan and the oil pickup was completely blocked with gasket material. She’s had me work on all her cars since.