Unfortunately, you can't rely on a Pleco to eat your algae. I have several Plecos and only a couple of them tend to eat the algae.
If you have a lot of algae, then it's best to get to the root cause of it. If it's a case of wanting a pretty Pleco then their are a few that you could consider, not necessarily black and white ones though.
L134s are not a great algae eater although they are beautiful.
I'm not really over run with algae and i do have shrimp and ottos i just thought it would be a bonus if it eats algae... and also saves me worrying about whether it's eating or not as no matter how many veg etc. i put down i never saw my pleco eat!
Thanks for that link will have a look. Is £30 a reasonable price for an L134, they were really beautiful!!
£30 is an average price for an L134, just make sure that it is in good health before you buy it. Check for sunken eyes and a skinny belly, if it has either one of these, then don't buy.
It never hurts to ask the staff at the lfs what they have been feeding them, just to give you a better idea of whether it has a good diet or not.
They are definitely worth buying although they can be extremely shy.
Good luck and let us know what you decide on.