To reward research I assign 25xp per level of spell researched - of course the research carries quite a bit of penalty itself and shouldn't be easy. Research is a lenghty project of trail and error, heavy on the error part. By way of example, the closest thing to true magical research done in the past 100 years would be the A-bomb. How dangerous, they failed on multiple occasions had lots of equipment failures and one catastrophic failure that resulted in the near immediate death of one researcher and thre other assistants being poisoned by rads enough for some serious health issues.
Spell research goes along the same lines as the magic shop in my mind, there is no wizard churning out spells at the rate of one per day anymore than there is a shop with 62 priceless magic swords hanging on the wall. But that's an opinion call. If there is an option to fail, there should be a decent reward, if there is no real challenge, there should be no reward.