As far as pain is concerned, they can also give you a shot in your cervix to numb the area, which supposedly (I didn't get one) stings but isn't awful and reduces the pain involved with dilating the cervix. Plus, as Down said, studies have actually shown that women who have had children report less pain than women who have not (Also, there's this interesting cohort study that showed that women who think the procedure will be painful actually report it as being more painful than women who aren't concerned beforehand and that, overall, pain reported during the procedure wasn't as bad as expected pain). So, have some comfort. Plus, I'd imagine that the pain from this (quick - think five minutes if even) procedure can't even remotely compare to the pain of labor and delivery.
I don't know if you have access to Up-to-Date, this medical service database that discusses diseases and the like complete with the latest literature (generally you can get it through your medical school's library), but if you or your partner do I would definitely recommend checking it out. It, among other things, shows all of the research stating that current IUDs decrease fertility, lead to cancer, etcetera as bogus. In fact, there's some studies showing that IUDs can actually decrease certain cancer risks.
I'm still cramping and spotting very occassionally post insertion (it's been two weeks now), but I can honestly say that the pain and post side effects of the procedure has been worth A. not being on the pill which left me with unwanted side effects even after changing brands a few times, B. not worrying about remembering to take the pill/picking up refills, and C. just knowing that I'm using the most effective form of birth control out there (surpassing both condom and birth control pill usage). Plus, it's good for 5-7 years (the Copper version is good for 10) which is perfect for me since I don't want any children during the next half decade or so. ;-)
Finally, have you definitely checked with your insurance to see that it won't be covered? Apparently mine would have been covered if my prescription insurer was the same as my medical insurer (it's not thanks to my university plan - so tempted to write a letter to the benefits office complaining about that) so that's why I had to pay for the device. Some people luck out though and end up getting the whole thing paid for. Depending on where you live and if you can go to Planned Parenthood (I just went to a family practice teaching service in an urban area which may in part explain why mine was so darn expensive relative to what I've seen online), getting it may be cheaper. Also, I guess you have to do the math also. If your IUD costs the $300 average and you go through say a box or two of condoms a month or so much money for your pills/patch/whatever, when does it even out?
Regardless, best of luck with your decision. Only you can decide what's best for your situation!