without the silly change "button" like my tiagras?
No
Not new, no.
Campag 9s work tho.
If you're looking at changing STIs then you may as well change chain & cassette and go 9 or 10spd.
Aye but funds are limited and chain and cassette are fine
[url= http://www.ebay.co.uk/itm/Shimano-105-STI-Levers-Shifters-8-Speed-/261099137108?pt=UK_sportsleisure_cycling_bikeparts_SR&hash=item3ccab8a854 ]these ones?[/url]
Oh, and checking http://beta.ctc.org.uk/cyclists-library/components/transmission-gears/derailleur-gears/shimergo it's actually Campag 10-speed you want to work with an otherwise all Shimano 8-speed drivetrain, hence http://www.merlincycles.com/bike-shop/road-parts/transmission/gear-sti-ergo-levers/campagnolo-veloce-10-speed-power-shift-ergo-levers-silver.html (though they do have a "silly change button" 😉 )
The button on the campy ones is in a much better place IMO
Why not look for older ones. Eg 8 speed Ultegra would be nice to use