I am in the north and i charged 30-45 on the few i did (detached, 3-6 gutters), spent 20mins-40mins on each. Are you doing other work their or just gutters? I will do alittle cheaper as an add on if im doing the drive etc and i sell the idea to them, if they phone me, its normal price. Supply and demand!
I guess it depends on where you are and whats acceptable, I also spent 2 hours doing a bungalow manually and charged £60.
I think add ons (up selling) are often overlooked in business, if you can add gutters to 1/4 of your jobs every month (assuming you have the time) you can add a few hundred quid a month you didnt have. Same for drains, algaecide wash etc. Over a year it could be a grand or 2. Again I will upsell products a little cheaper than normal as a hook and hopefully build customer awareness and the likely hood of repeat work.
hth
steve