Maybe you could have dealer/ ship yards that cover just a few ship manufacturers (or even just one)?
When you think about it Stations cram an awful lot in (Police / trading of goods, ship repairs, ship outfitting and modifying, ship sales)....
Maybe it could be an idea to separate some of those things to another station / ship yard that handles ship sales, equipment fitting and servicing?
When you think about it in RL terms you drive your car to the supermarket and buy goods, you may use the supermarket to do some banking at the ATM but wouldn't buy a car at the supermarket (unless ASDA are trying to muscle in on yet another market), you wouldn't have parts fitted at the supermarket or a service done. You may buy fuel from the supermarket and regular consumable items associated with driving though.
Would a similar perspective work or be applicable in oolite?
This was previously done in the S.I.R.F oxp http://wiki.alioth.net/index.php