julian's point is a good one.
I looked into a share in an Arrow I, but was put off when the owner mentioned his annuals were typically around £9000 each!
I'm guessing around £3k pa of that was due to the retractable U/C. That's 40 hours 'free' flying in a PA28-235/236.
Of course the engine overhaul costs will be greater for the bigger engine, so annual costs are not the only issue.
tp