I havent but my sister used one for some documents when going to Australia for a year. It cartainly wasnt cheap, but get a quote from a couple- she found a huge difference in price, although had a lot that needed signing.
A Notary is just a solicitor. As Marcros says - get at least a couple of quotes.
However, are you sure that you need a Notary to cash in travellers cheques? Just two years ago I had £300 of traveller's cheques left after my holiday and just paid then into my bank account - no fee, no problem. The alternative is to spend them. Youcan spend travellers cheques in the Uk just as easily as you can overseas. Most large store will take them fro full face value.
Travis - this side of the Pond, the Banks don't give anything for free!
Misterfish - it's a bit more complicated than what the PO can do.
My mother left a Will, with my Sister and I as beneficiaries but no named Administrator or Executor, but by mutual consent I have been acting as such and because of the relatively small amounts of monies concerned have managed to resolve all other issues without going for Probate.
The banks over here would not deal with the Cheques so they had to be sent over to Amex in Utah - they are worth about £2k but Amex are now seeking other legal proofs!
Beginning to wish I had donned a wig and forged her signature! :?