Whatever about price, i have found greyhound's service and customer service to be abysmal. I switched about three years ago to Thorntons and there's a world of difference. they are a pleasure to deal with.
I have experience of Panda with a commercial account, and it's not good.
Check out Thornton's Eco Band Lite, where you get a 25kg monthly allowance before extra charges. It's €210 for the year now, but will increase by 17.88 in January. If you don't produce a huge amount of general waste, this should be sufficient.