Can't help with the the discount side, but if you haven't made your mine up about tyres heres my opinion on what i've used on st4 and st4s over the combined 24,000 miles.
Metz mez4 complete shite but never wear out,best thing u can do is give them to capt. gatso.
Michelin pilot sport grip quite well and last about 4000 miles front and rear.
Pirelli Dragon Corsa, excellent grip, good for use on track but history after 1500 miles, will do just over 2000 miles if u like riding on square tyres.
Bridgestone bt010 great all round choice with good grip and reasonable wear. OK for the odd track day if you're not the quickest bloke on the block. 4000 miles out of rear and 6000 miles from front.
2 very important points are they are good in the wet and still feel good when well worn rather than having that 'oh gawd should have changed the tyre feeling'
Bridgestone 012 better grip but lot less life than 010.
Finally for work bikes that do big miles but still want decent grip in average brit weather try Bridgestone 020. Not a trendy,i'm a hero type tyre but works very well on a variety of courier bikes.
Sorry if i've repeated what you've been told already but Bridgestone 010 is a very good all round choice.