Like others say, if you feel guilty and can't get past your guilt, donate them to charity. I personally wouldn't feel guilty a jot, I think we do a demanding job that, though is by the hour well recompensed, is without holiday pay, sick pay, is precarious and sometimes even dangerous (like other jobs can be), is socially stigmatised and incorrectly thought of as easy. I work hard and I'm happy to enjoy whatever little pleasures or perks the job throws my way and I think you should too
The only concern I have ever had when receiving more expensive presents is if they come with obligations down the line, a way of emotionally blackmailing me into letting them into my private life or something. Thus far, luckily that hasn't happened, but having said that I've only ever received a small handful of presents in the £200-£400 range, like most people I've mostly just got choccies, books, sometimes perfume, and the odd mid-range dinner (and a once a Wetherspoons breakfast! bless him).