From reading others' experiences, I'm not sure there are any that accurately replicate the shape of genuine SMP.
Steve Hogg's and Pearce Coaching's pages are a little out of date now (SMP line-up has changed), but will give you an idea as to which model is likely to suit you.
Then you can look for a cheap/beat-up version with the same base: the heavily padded/ugly coloured models tend to go cheaper and you can strip and reupholster them easily for a few quid.
From reading others' experiences, I'm not sure there are any that accurately replicate the shape of genuine SMP.
Steve Hogg's and Pearce Coaching's pages are a little out of date now (SMP line-up has changed), but will give you an idea as to which model is likely to suit you.
Then you can look for a cheap/beat-up version with the same base: the heavily padded/ugly coloured models tend to go cheaper and you can strip and reupholster them easily for a few quid.
Check the SMP thread for "how to" posts.