Citrix V’s Windows TS

We have an Oracle App. using Oracle Forms 6i for the retail sector and wish to deploy it over the wan. We evaluated citrix in a pilot program and are happy that it will do the job quite well. Problem $$$$ !. The other option is Windows Terminal Services which appears to be cheaper but we are not quite clear on the differences or bits missing that allow it to be cheaper. We have a requirement for printing and use of remote com ports on the remote POS units. Can anyone lead me to comparison papers or have gone thru the same evaluation route.

Any pointers will be appreciated !