can anyone tell me if its possible to still purchase one of these whistles in key of C or D and where if possible.
or is there a whistle of similar quality with a tuneable head that anyone could point me in the direction of.
I think your best bet is to visit here regularly, pay your fees (just kidding), and check for sales of used ones. Also, check irishflutestore.com for the occasional sale of O’Riordans. I’m not sure if Pat is taking any more orders and so you’re looking at the used market and high prices. I’m told Pat makes appearances at a festival in Indiana once a year and has some to sell. Lines form early.
Your question about a similar whistle is a tough one. You’d need to let us know what it is about the O’Riordan you like and then people might be able to think of whistles with similar qualities.
i like the tone and true sound of the o riordan whistle and the fact its tuneable too with the sliding head i would be interested in any whistles of such quality and i would prefer the whistle too be available in african blackwood.
any advice would be great,i would like too buy a better whistle.
the o’riordan seems too tick all the boxes i want with good tone and its tuneable and also in blackwood i would consider any other that can offer this and is available.
Well, I can’t speak to the O’Riordan at all, never having played one.
If it’s blackwood you favor, though, I can put in a very good word for the whistles made by David O’Brien in Canada. http://www.obrienwhistles.com/
I recently got a blackwood D Rover set, (3-piece), in a trade with another C&F poster. I love it enough that I asked David to make me a C tube to go with it. It arrived today, and for the life of me, I don’t know what I’m doing here writing this note to you right now! 
O’Riordan concert whistle can cost you. A lot of the times they are aluminum, but the blackwood ones can go up there in price. If you have the money, it is a great investment, and well worth it.
Doc Jones just had 2 aluminum O’Riordan whistles in D & C on his website, The Irish Flute Store. As of last night he still had a O’Riordan low D/Eb combo available. Doc would be a very good person to get in touch with when hunting for any whistle. He would also have a pretty good idea of which whistle might match what you’re looking for, whistler. (BTW, I own no part of The Irish Flute & am not being reimbursed for this endorsement.)
After a brief acquaintance with an O’Riordan, IMO a Rose or Abell whistle might meet your needs, both available in blackwood and tunable … with the warning that everyone gets a different sound from a whistle when playing. To my ear a Rose would be very like the O’Riordan. Your mileage may vary. 
Thanks for the replys i might try a few whistles before i finally get an o’riordan in blackwood - i want my next whistle/s in key of C and D.
I will try some out and settle on what suits best but i eventually want the whistle i mentioned.
Pat does indeed sell whistles at a festival in Indiana. I just bought an A and Bb set this morning. (I’m not bragging, just very blessed.) The festival is called the Johnny Appleseed Festival in Fort Wayne, Indiana. It is held the third full weekend in September. The line forms around 5:00 a.m. They are expensive but worth every penny! He is a delightful man and I wish him good health for many years to come.
That one’s had a big SOLD plastered across it for a while now.
Abell whistles
I’ll second Jim’s suggestion of the Abell whistle. I have a high D and love it.
I live in Fort Wayne, and Pat has been a friend of my uncle for decades. I have a healthy collection of his whistles and they are the brightest, most easy playing whistles I have ever used. He doesn’t take orders anymore, except from his celebrity clients, (Joanie Madden is his favorite name to drop) but he makes about two dozen to sell at the Johnny Appleseed fest every year.