Can't comment on how easy it is to check rockers as the shop did it when I had my belts changed.
Much cheaper to buy in the US - getting on for £90 here, $54 per rocker at Section8superbike, $59 at Ducati Seattle. VAT and import duty works out at around £7 per rocker (if you're lucky the vendor may mark them as low value items),postage $75 with Section8, an amazing $13 with Seattle.
You can get them re-plated and they then should be better than OEM but it sounds a fairly protracted process; MBP seems to be the company usually mentioned.
The general consensus seems to be that good warm-up procedures help a lot in preventing degradation.