count the total number of turns in the original coil times the circular mill for that wire size. that is your "slot fill". after you determine the number of turns you need for your new winding, take the original slot fill divided by the number of new turns and that will equal your new wire size.

do a google on EASA. easa stands for "electric apparatus service association". that will list all the rewind shops in the world that are members. it will give you state by state motorshops, where they are as well as contact info.

the guy who quoted you $300 should be taken out and hung. most of the materials you need can be obtained from wondermagnet. many of the materials can be improvised.

hope this helps,

Here are some tips....
Knowing what your expected output current will be you want to have at least 300 CMs per amp of current. And try and keep magnetic densities in the Tooth and back back Iron close to what the original manufacturer had assuming your going to running in the same area for Hz output. If your above this reduce 10% for every 10% you go above (The Iron losses are not linear but your screwed about above 100 Hz with 60 Hz lams so don't go there). If your lucky and can get below 60 Hz I would increase any where up to 25% if your down as low as 30 Hz (not likely but good luck too you).

Materials....
Can't buy DMD at a reasonable price? use Mylar sheets cut to size.
Varnish, by a can of Fiber glass epox resin. Its not as good if you over heat it but its better than nothing, or you could paint the new windings with many coats or Glyptal 1201A insulation paint ( Tough call, the epox is faster and thicker but the glyptal has better true class F insualtion rating ).
You don't need wedges if your under 2 kw, but I would splip some mylar over the tops of the slots and be sure lace up the nuckles of the windings with butchers knots to keep them from trying to move when you pour epox of varnish.