Maidenhead aquatics are expensive and small - twice or 3x what you'd pay on eBay.Have you looked at your local shops? Maidenhead Aquatics sells shrimps, though different branches sell different colours. Maybe give your local shops a ring to see what they stock?
If you want a specific type, you do need to buy on-line. I know that ProShrimp isn't selling shrimps at the moment because they don't trust couriers to get them to you overnight.
When I drove, pre shrimp days, I used to go to many lfs bit don't anymore. There was a fish farm fairly close that always had fish at the best prices locally but I think it closed just as shrimp were coming onto the market so at that time expensive. So not really in position to comment more widely outside of what I've mentioned.I must admit I've never bought shrimps from Maidenhead Aquatics, or even looked at the price, I have just noticed they sell them. Mine came from other local fish shops and they cost a lot less than the price you give for MA.