Are the techniques involved in Uilleann Piping similar to those in Highland piping. I am a highland piper and was wondering whether my skills learnt in playing those would make it any easier to learn the Uilleann Pipes. If someone else who has done this cross over could give me an info it would be appreciated.
Is the finguring similar to highland pipes or more similar to the tin whistle or neither?
Teflon
The fingering is similar, but different. A lot of Uilleann Pipers also play tin whistle…which is a good instrument to practice on while you wait for your practise set to arrive, its fingering is also similar to UPs. You will have to put aside the majority of what you have learned in the gracenote department, not neccessarily forget it, but most of it is not used on Uilleann Pipes. The bag pressure will also differ, being lighter on the Uilleann Pipes. I think that you will find the biggest challenge is using a bellows instead of your lungs. Getting used to using it properly in conjunction with the bag-arm is a big key in keeping the instrument steady in tone. The thing to avoid is using the bellows itself to maintain a steady tone…that is the job of the bag-arm, the bellows merely supplies the air.
Bottom line, if you know how to play another form of bagpipe other than Uilleann, the learning process is much easier than taking to it from scratch. But, it is a tricky and sensitive instrument (and for some if not most, that never changes) which requires a lot of practice to play well…something I am reminded of on a daily basis. 
So, go ahead, get a practice set…you know you want to, you really, REALLY want to. C’mon, just one little practice set won’t hurt you… 
Hi Teflon
There are quite a few of us out there that play both GHB’s and UP’s. As well as what Joseph has said I would suggest order a decent set as instead to purchasing something from ebay. When there are good sets on ebay it is quite difficult to obtain one. You will have to get used to the fact that uilleann pipes are expensive. You can search this board to find lots of info on pipe makers.
If you don’t know anyone who can teach you try to find a Uilleann pipers club in you area, if there is one.
And, when you think you know who a decent maker is, PM a couple of people who are frequently cited here as being authoritative and ask their opinions…and start again 