I've done all of mine myself with the exception of two, but that's simply because I was unable to go and get them to matte so I had to have someone else do them. It's not that hard. But you will make mistakes the first couple times.
If you are not making any prints longer than three feet, I'd advise you to get one of these: [link] It's not very expensive and has everything you need to do a good job. You will also need a roll or two of archival framer's tape, some Bainbridge matt board and some spare blades. As for frames, just do a Google search for "inexpensive custom picture frames." These will be "some assembly required," and you will get to choose from several types of acrylic or glass. If your stuff is going into a gallery, trust me on this: get the antiglare kind (you don't know exactly where they are going to display it or what kind of lighting they will use). As for acrylic or glass, acrylic is harder to break and is a little lighter, glass is marginally clearer and bows less.
I've had a lot of success with doing it myself, rather than letting someone else frame things for me. the actual process of putting the frame together isn't that complicated.
for prints that are standard-sized, I buy the ready-made crap from walmart or similar and a mat to go with it (if the frame doesn't come with one). I choose neutral styles like matte black so it looks fairly 'professional' without the associated cost. it costs about $20-$40 to frame something this way.
for big or strangely-sized prints, I buy nielsen-bainbridge frame kits (purchasable at frame shops or from the internet - internet's usually cheaper) to fit the print, and then have glass and a mat cut for it. you can get glass cut at a frame shop or a hardware store (the hardware store is a little cheaper sometimes), and mats can be cut at a frame shop or by you with a mat cutter (as Fallis suggested). all I need after that is some frame wire, tape, a screwdriver, and a little time. it costs me about $80 on average to frame something this way. I just did a 24x24 frame that cost me $86 I believe.
another option entirely is spray-mounting the print to foam board, and then cutting off the excess edges with a VERY sharp razor blade. I use a standard boxcutter and change out the blade every time I do about 48 inches of cutting - you can buy 100 blade packs very cheaply. then you just tape or glue frame wire to the back - some people (very carefully) paint the edges of the foamboard black to give it a little 'class' (or they simply use black foamboard, which is much easier!). I leave mine white as a personal preference. it costs like $10 / print this way and it actually looks pretty good. I do this when I have to prepare a lot of prints for presentation.
"...so it looks fairly 'professional' without the associated cost."
Forgot to mention this until now, but it can look a lot better than professional. Last "professional" mat I refused to pay for had three of the corners overcut and the cutter obviously had a dull blade. Mine never have those problems. You wouldn't believe how much they wanted for those mats.
I like to purchase my frame kits from American Frame - the price and quality is good.
I don't like the really cheap frames, mostly because the glazing is a really cheap, thin plastic which really shows (even small frames tend to have a bowing problem).
For glazing, I definitely prefer acrylic over glass. Lighter and far less likely to break in shipping. Most galleries today require/prefer acrylic rather than glass - especially with larger frames.
For matting, I've always preferred to cut it myself. I had good luck with the logan system of matt cutters - although I probably need to get a new one soon...
While the standard for generations, spay and dry mounting are no longer considered archival - the current recommended method is a T-Hinge using archival framers tape. The theory is that you should always be able to remove the art from the matt in case the overmat or backing mat starts to deteriorate.
One other option is to get a heat press and permanantly seal the print to a sheet of matt board, although that is kind of expensive. On the positive side, it's pretty much the ultimate way of flattening uncooperative FB prints.
Trust me on this: Buy a mat cutter. It is one of the most worthwhile investments you can make. One set of a dozen mats and it will pay for itself. Personally, I like the Logan brand. I've cut ... well... I don't know how many mats -- lots. To have someone else do it would have cost many, many times what the mat cutter cost, and they probably would not have done as good a job.