hello Kaz,
I have only had bees for 3 years now and the first 2 they more or less looked after themselves . Then last year a swarm moved into an empty hive I had . So I am by no means an expert !!! however, I would say they are easy to look after , just needing certain things doing at certain times , but nothing too involved really . As for costs , well it depends on what you want to spend really.
http://www.thorne.co.uk/ I was lucky and got given my first hive including bees, and then I got a load of stuff off of freecycle , about 4 complete hives plus loads of spare supers and brood boxes plus a beekeepers suit , acouple of smokers, hive tools and a pile of odds and sods, so as I say ....very lucky . The thing is you can get hives second hand quite cheap , or even free. If not then you can make your own , or buy new ones....the Thorne's link above will give you all the costs of everything you need, but although if you bought it all new , it would be dear , it does last more or less forever. Ithink the beginners kit starts at about £225 , if you buy flat pack and put it together yourself ( very easy to do !!). The bees are a different matter....you can either buy the as a nuc...thats a small nucleus colony that grows over the first year or so , or you may be lucky and see a swarm you could catch, look on youtube to see how it's done . Easy as long as the swarm isn't 60ft up a tree....

Or you could go to your local beekeeping club and see what's what there , someone would no doubt be able to help you out with a nuc.
As for getting stung ... well yes you will ...

The first colony I had were very touchy and went potty when I went anywhere near them ,as I found out one day when I went near the hive while I was pulling ragwort. They went mental , and I got stung maybe a hundred times....the little sods chased me across the field stinging the cr*p out of my neck and face. However , even that hive has calmed down a lot now , and I never get stung by them . Nor do I get stung by the swarm that is now a complete colony in my other hive. I am lucky in that bees stings have no effect on me (apart from feeling the initial sting that is ) , my niece isn't so lucky . She has to carry stuff with her in case she gets stung by them as she is very allergic to them . So as long as you are ok with bee stings , all should be ok , you may be like some people and never get stung !!! You can use the honey instead of sugar , plus you can use the wax for candles and all sorts of cosmetic type things. Are they worth keeping ? YES very much so . Are they interesting ? YES , they will keep you entertained for ages just watching them fly in and out of the hive , plus seeing what they do in the hive is really fantastic. Don't be put off by getting stung , it may never happen ? , and even if you do , it isn't really that bad...no worse than stinging nettles anyway. Hope this helps a bit ....
cheers
Russ
ps: here is the swarm that moved into a spare hive ,
http://www.accidentalsmallholder.net/forum/index.php/topic,680.0.html