I usually say customers that try and haggle "I'm not a car salesman, would you go in to Asda or Tesco and ask them for discount?"
If I get the feeling they are going to be hagglers then I usually add a bit on and then say usually it would work out at that, but since you're looking so much done the best I could do is that, and give them the real price.
If they think they're saving something it seems to stop them asking for discount, and they think they're getting a bargain.
If they still want to haggle I just say I'm sorry but that's the best I can do for the quality of materials and service I provide, 1 year warranty on all goods and 2,3&5year on various LED lighting products.
I dislike labour only work as quite often the client still expects repairs done free, But do provide labour only for any larger jobs for a few long term clients that are vat registered businesses, being that I'm not vat registered. The small jobs I do for them just get billed the same as anyone else.