Spending up to 200 dollars now on a bike for slow rides on gravel roads
I'd recommend another used bike.  It might take some time to find a suitable one that fits your budget, but garage sales, thrift stores, and maybe even Craig's list are good places to find good used bikes that would fit in your budget.

A couple of recommendations:


Don't buy a bike without seeing it.
Bring a set of decent tools to do a good inspection (Don't use cheap tools on someone else's bike...)
Loosen and remove the seat post, look inside for bad rust/corrosion
Do ALL the parts that are supposed to rotate/move smoothly? (A rusty chain is no big deal - it can be replaced, but count that in your budget)
See if you can loosen the pedals from the crankset
Remove and replace the wheels - you're going to have to replace tires and tubes eventually...
Check cables and brake pads (no big deal, they might well need to be replaced, but count that in your budget)
Loosen the handlebars and headset


Obviously, you'll have to be able to return the bike to its original condition.

If you can't do any of that without damaging the bike, it's not a good bike to buy.  For example, if you can't get the seat post, pedals, or headset loose, there's probably way too much corrosion or rust.

If the seller doesn't want you to check out the bike like that, don't buy it.