Big is quite correct, though there are a few other factors to add to his thoughts:
Though the 150D is a bit of an odd model in the range, there are still many used servicable parts available, which are not yet for the Skycatcher - you have a choice where you buy parts with the 150.
Yes, you might have to replace or overhaul something. As long as you budject for it, you're still okay. Once the new or overhauled component is on the plane, the valuae of the plane is greatly increased (though don't fool yourself into thinking all of the paid amount is seen in increased value, just a lot of it). You can, though, fly the aircraft many hundred hours without the increased value decreasing much. So, pay the $15,000 plus re n re for the engine if it needs it, and fly off 500 hours, the value will even itself out in retained value of the aircraft, and that large amount you did not spend renting that 500 hours!
With a used 150, there is a better chance you can find someone to let you help with it's maintenance, and you'll both learn, and save a buck.
With the used 150, you can choose to not insure for hull, and take the risk yourself. The truth is that if you crash it a little, you have quite a bit of airframe to sell for parts. Even a prop struck O-200 has quite a bit of value. If you crash it a lot, you won't care, and you wife won't want what's left anyway... If you actually put the hull insurance premium you would have paid in the bank as a reserve, and fly with lots of care, and a little luck, you will profit over the long term. Fly it as a beater for a few years, with no hull insurance, then when you've saved more money, fix it up, and insure it properly. That's what I did...
There are very few "great deals" in aircraft purchase, just good business decisions, if you were prepared to rent all of that flying elsewhere. You will still be paying the costs, but at the end, you'll have an asset to sell. It might appreciate a little, and offset your flying costs.
150's are very reparable. Even if your thorough pre-purchase inspection turns up a defect, look at what it would cost to fix it, the purchase still might make good sense.