The club shop is a missed opportunity to exploit a valuable income stream. As has been mentioned they frequently sell out of common sizes, you should be ordering more medium and large sizes in as these are the most popular.
The stuff they get in off their own back just looks poor quality. They have chosen Joma and made mention that there would be all manner of training wear and kit available which simply hasn't materialised. Kits have sold out with no option to even pre order on the website.
The fact is the club are to be run as a business then they need to sort it out as people would spend money but they can't buy what isn't there for sale.