After lots of searching, I've finally found some monogram sources.

First, an email ad from Joann's says they now have 6' styrofoam letters that are paintable (they recommend "Smooth Finish" paint also at Joann's), for $1.49 per letter. A possibility I have not as yet checked out. These could be painted and swarovski crystals glued on, with probably several ways of attaching them to the cake.

On eBay, Item #5591087250, Mirror Monogram Initial Letters Wedding Cake Topper. This is a bid auction, he starts them at $25 for 3 letters, 1/8" mirror-back plexiglass ("looks exactly like mirrored glass"). Center letter is 5" side letters 3" w spikes. $10.00 shipping. So far only one type letter, but I emailed him today to ask if he will put these into "Buy It Now" sales instead of auctions (so no wait to order them) and if he will be adding new fonts.

Also, eBay, Item #5589834392, Monogram Wedding Cake Toppers, set of three letters $30.00 shipping $6.00. These are from "Cake Jewels", and are white resin, paintable, and have several fonts to choose from.
They also have single letters #5589836112 for $15.00 that are 4".

There are wooden ones, #5591256020, that are 7" w a 2" spike. These are 1/4" red oak plywood, sanded smooth, $6.50 each and $6.50 shipping.

You might also want to check out www.craftcuts.com for the plexiglass letters, I just can't quite figure out their pricing for sure, but they sure have a wide variety of fonts to choose from.

The crystals are #5589652942, Designer Trends by Tami. She is now selling a Swarovski Crystal Mix for Monogram Initial Cake Toppers.
You can get your choice mixed colors, 250 total (50 4.8 mm; 100 3.9 mm and 100 3.2 mm) for $19.99 BIN, $1.50 shipping. She has lots of other packages of sizes and colors.

Maybe now we can make these for our clients instead of having them order from somebody else and pay a $150 or more! I'm going to try it, I just haven't decided which to try! Janice

Thanks for all the work Janice! Keep us posted on your progress. Don't forget that walmart has wood letters that have a hole in the bottom for a spike for $.99 a piece.

I keep putting those letters on my Walmart shopping list, and then when I go I forget to look for them! I have to use the electric carts, and even with that wonderful invention I can't stay with the shopping too long. Have to go to Wallyworld soon...will write them down in large letters so I will go see about them! Thanks for reminding me.

I really like the mirror looking ones, the styrofoam ones would be easy on the cake! I don't know much about the resin, it seems like it would be a little heavy, but it doesn't say how thick they are so that would make a difference.

I AM determined! Janice