To use car terms, you can get a £1000 small car with high mileage, but cheap to run or a new BMW with a huge engine and costs to match.
I did look at the Microlights (That's how I first happened upon the whole thing really)
There is a weightshift microlight on the same field as me that the present owners found neglected in the back of a hangar and bought for a few hundred quid. They cleaned it up, got it checked out, renewed the paperwork and now they fly it at very little cost. OK, it's not top of the line but nor is it a tatty wreck and it flies, so it can be done, though it probably needs a little patience.