In reply to iusedtoclimb:
I'm not sure about second hand suits but a a couple of features/fit you want to look for
- good mid level suits have thicker hip and lower torso areas. This helps with lower body floatation which is typically poor in anything other than good (by good I mean trained seriously for a long time as a kid, not 'won't drown when swimming the sea) swimmers. Cheap suits won't have this, and advanced level suits don't need it.
- shoulder flexibility. You should be able to swing your arms around with little, or no, restriction on movement. If you haven't worn a swimming wetsuit before you'll find it surprising how good this can be
- very snug lower back area. If this is too loose then it will fill with water. Not a good plan
Have fun, as in intermediate level swimmer swimming with a wetsuit on feels like being turbo charged.
Oh, and don't kick too much.
(edit: doubt you'll need to cover the feet, September is the warmest month for water)
Post edited at 08:44