Are you really sure you want a telescopic one? They jam, don't like sand and do telescope in without warnings on occasion... I hate the stuff.

I use a simple carbon tube, nothing fancy, nothing to break. Buy them in pack to get a good rate and buy some with a fairly thick wall and multiple layers of carbon at different angles. A bunch of companies on the web sell them for reasonable prices but you are better off finding someone local as long tubes are expensive to ship. I recall a price of £14 a piece last time we shopped for some, shipping included for a pack of 10 or so.

Once you have the tube attach a quick connector at one end and glue a golf club grip at the other end.