We set up and run our own scheme for the same reasons – to cut out the third party facilitator. This enables us to purchase bikes direct from any retailer, negotiate discounts and take advantage of any sale offers.
It is a simple process to set up and administrate, and once running we had ours approved/cleared by HMRC just to be on the safe side.
If of any use, I could e-mail info on our scheme which includes all the standard forms required.