There are a few good options around these days.
Steward's and Optilabs supply the Zeiss/Zeiss - style frames with own brand lenses. The frames last a lifetime, lens choice is limited but they are good value - you can get a couple of pairs sub £300 if memory serves.
Lots of places supply Oakley prescription eyewear (myself included!) but they have moved away from "shooting specs" these days (with the exception of the Tombstone frame) and now just make generic sports glasses. There are no prescription shooting lenses per se but the general lens quality is excellent. Prices for one set start around £350
Decot supply "proper" shooting glasses from the USA with lots of lens options. Ive only seen one batch of these: a client bought five sets, all had incorrect prescriptions and the lenses were poorly made. Couldve been a one or five off..?
Along these lines are Straub and Castellani - popular abroad, don't know much about them over here.
My main products are Randolph Engineering (the Sporter, Classic and Edge frames are good) and I am running the prescription program for Pilla UK. Prices are higher for these, frames start at £145 for RE up to £180, £189 up to £249 for the new Carbon Fibre in the Pilla collection. Lenses start at £260 for an uncoated set. Antiglare coatings, hydrophobic coatings, high index and bifocal options are available on request.
Pretty much any prescription can be handled and results so far have been excellent!
If you have a prescription copy to hand i can give you some tailored advice.
Ed