Never heard of powerchips.
this forum has a good variety of remaps with costs anywhere from £200-500
REVO
APR
RTec
Jabbasport
AMD
P-Torque
Shark Performance
PDTuning
DNA
RS Tuning
Bluefin(superchips)
Other ones i can think of, but aren't very numerous are
Giac
MRC
Morego
Angel tuning
As you can see, theres lots of options, just from looking at what guys on here are using. personnaly i would stick to a known quantity.
Have a flick through the VAG forums such as briskoda (octavia II section), seatcupra.net (mk2 leon section), this forum and the other GTI forums and you will see many reviews (both positive and negative on pretty much every one of the tuners above). Have a read of all the options and dont just buy based off price.
Also consider aftersales support, reliability, their experience on the engine, and then consider the cost.
Theres plenty of guys on here(myself included) who have started off with one tuner and then swapped to an alternative vendor because they werent happy with it anymore, or realised it wasnt as goood as they thought. So its not always cheaper to go for a cheaper option in the long run.