They probably are, I've refitted tees for myself ('girly' tees ride up unless I give them a nipped-in waist) and it's not hard at all as long as you're just working along the sides. Tailors probably won't do it because it's too easy, believe it or not, it's like asking a mechanic to move your mirrors for you. They'd be spending all their time measuring you for what's about 2 minutes (for them) worth of sewing- not worth their time.

Someone recommended Generation T upthread, that's a good one with some redos and recycling, but not so much on how to refit things. This is how I taught some very manly Marines how to take in baggy uniform shirts, so if they can do it, you can. This takes me like, two minutes to explain if you're in front of me, but since I can't be there to show you, I'm gonna lay it all out. GET READY, CAUSE HERE WE GO.

I would recommend getting some cheap (throw-away quality, we're going to mark them up) t-shirts and binder clips. I'm assuming no side seams because it's cheap! (if it has them, just use them instead of this next step) Before you put it on, lay it flat, take a magic marker and run it up the sides to mark the 'seams.' That way you're not twisting the shirt when you start the next step.

Put the t-shirt on inside out. Make sure the seams are straight along your sides. This is important! if you neglect the sides, your seams will look all wonky because things won't match up.

This is where you're probably going to need some help. Take the binder clips, and working one at a time on each side, nip in the shirt along your waist from under your armpits to the very bottom edge. Try to get the binder clips as close to touching as you can- we're looking for a line to trace. Also, make sure the seam is in the MIDDLE when you pinch and clip-if you have to kinda fold it and roll it, that's okay, but keep the middle where it's still centralized. Don't go for 'skintight,' go for 'closely fitted.'

Take a magic marker and trace from top to bottom on the front, where the ends of the clips are. Try to trace them in the back, too, or if a friend is helping you, have them do it.

One you've got your shirts all marked up, take off the binder clips, and lay them flat again. the front line and the back line should match up, but if they don't fit exactly, it's okay to fudge it a little so they do.

Draw another line INSIDE THE SHAPE, about a half inch smaller. This is for what's called the seam allowance, it gives you the fabric that will be between the sewing line and the end of the material.

Cut the two SMALLER shapes out of the sides. They'll be diamondy or whatever depending on your bod and the shape, but most importantly, they should be symmetrical. There should not be any lumps and bumps, there should be gentle curves or straight lines going into gentle curves.

Leave the shirt inside out. Using a sewing machine or really straight hand stitches, sew the front to the back on the markered lines. Try it back on. If you need to rip out a seam or take it in a little here and there, go for it- just remember to keep your seams as flowing as possible.

Once you've got your t-shirt 'pattern,' you can probably keep the parts you cut off the sides to use as a template for other t-shirts. Just trace it on the side (using chalk), cut out the shape, remember how much space you left as a seam allowance, then sew it back up.

Some tips- got from directly at the armpit seam to all the way at the bottom, or else you'll have an odd 'corner' when you're done.

If you need 'a boob sock,' (where there would be like, an actual 'shelf' in the material for it to fight right) a) Va va voom, and b) This won't work for something like that- you'd need to use darts, and that's advanced.

If you do this right, you might not even have to throw away the shirt- I taught some Brownies how to make a similar project (A dress for their dolls out of an old shirt) and about half of them couldn't see the marker lines when they were done.

You can pick up a good basic electric sewing machine (I like Brother) for about $100. Also ask any relatives if they have one you can borrow first to try it out. (My first sewing machine was my mom's old one she hadn't thrown out just in case.)

Good luck!