Nick, Do you use a new ball each innings?
I'd be a bit annoyed if we provided a £17 ball and the oppo did a £12 ball!
not always but it can happen. You do get what you pay for. We found out the models before our first season in this league and tested each type in the nets. We concluded the £17 was the best in the hand/seam and swing but the £13 ball wasn't fair off. The £12 ball was disliked by everyone. That's been our buying policy since. Don't think many clubs buy the £17 ball, most go for the £12 one I imagine.
Regarding our usage, If we bowl first we tend to use a new ball, the only exception is if we know the oppo are rubbish and a bar of soap would do!. If we spank up a huge score batting first we tend to use an old one, something with 20-30 overs use ie. we bowled an oppo out cheaply but it still remains hard with shine. Due to the price of the balls, alot of clubs reuse balls, for example we ordered 24 balls for 40 matches (2 teams) this season in an effort to keep costs down (ball bill £317!). We are lucky that we have a few of balls from last season with minimal wear that can be polished up. Plenty of clubs end up using soft old balls with little or no shine. Some clubs are a bit devious and buffer up an old ball to swing from ball one - but it doesn't survive long.