If we set aside Ebay and hardpoints, my researches to date suggest that the choice is as follows;
Veritas, as already recommended. 12" blade, 2 1/2" depth, 12tpi rip or 14tpi crosscut. About £55 - £60 a pop.
Atkinson Walker kit as supplied by Matthew (Workshop Heaven). 12" blade, about 3 1/2" depth (as far as I can tell from photos), either 13tpi rip or 15tpi crosscut. Make your own handle to taste. £55 a pop.
Flinn Garlick Saws Pax 1776 - several configurations, 8", 10" and 12" in either 15tpi or 13tpi crosscut or rip. Blade depth 2" for 8" and 10", 2 1/2" for the 12" saw. Prices between about £80 for the little 'uns to about £110 for the 12".
Pax 1776 'special' supplied by Matthew - 14" blade, 3 1/2" (?) deep 13tpi rip or 15 tpi crosscut, £130.
Flinn Garlick saws 'special' Pax 1776 18" 9tpi - huge thing best suited to framing work - £150.
Lie-Nielsen 12" x 3" or 14" x 3 5/8" 10 tpi rip, or 12tpi crosscut. About £140 - £150. (APTC)
Lie-Nielsen 16" x 10tpi about 4" deep, £152.
Several 'old' Pax, Lynx, Roberts and Lee etc. saws from Flinn Garlick. The blades will be fine, but many people will want to reshape the handles. Mostly in the 12" crosscut range, about £40 - £60.
Anybody know of any others?
Edit to add - Flinn Garlick Saws now offer Roberts and Lee Dorchester, choice of sizes, 14" x 13tpi rip, 3" blade depth, walnut handle - £95. They also offer the Lynx range, eg. (14" 13tpi rip, 3" blade depth, £90), and another 'budget' option, not available in rip filing, for under £50.
A good perusal of the Flinn Garlick website would be time well spent - they offer plenty saws and plenty other than saws.