Futaba Tx module:
http://www.hobbystores.co.uk/default.asp?itemid=Y-MA2214
A Tx only board would be great, but it would need to fit inside the module case to make it 'nice'.
I haven't built a Tx as yet, but will mash something together to try out on one of the boards I have from you.
I'll get you some dimensions from my Flytron board/module...
At a guess, the width will need to be around 33mm and the length is around 55mm.
EDIT
How about a Tx board that would fit inside the width of a Futaba case, and fit inside a JR module case as well (by making the length of the PCB fit the width of the JR case as they are wider than a Futaba case)?
JR case
http://www.jrradios.com/Products/Default.aspx?ProdID=JRPA615
Could be do-able by using coax for the antenna and short ribbon 'jumper' cable for Tx inputs?
Just a thought...
/EDIT
Nigel.