Almost all the lightbulbs we use are LED now - leccy bills have gone down loads , it's very satisfying, esp with the halogen replacements! (We used to have 6 x 50w in our kitchen, 300w per hour; we now have 9 x 5 watt, 45w per hour, less than a tenth of our old wastage usage).
I sourced most of them from the internet over the last couple of years & paid £6-£7 each (I think) for 100W equivalents; however, today I went to both B&M & Home Bargains & discovered both have lots in now. (Actually I just checked back on amazon & I paid £6 for one GU10 5 years ago; the same bulb is still £6 there today but I got 2 better Philips ones for £6 from B&M)
B&M have Philips & Ever Ready at approx £6 for 2, although the Philips only come in bayonet & large screw fixings (plus GU10), & only up to 60W equivalent, while the Ever Ready also have small screw, & do have some 100W equivalent in the bigger bulbs (but those are £8 for 2).
Home Bargains bulbs are cheaper but in a brand I don't know.
If you'd prefer light similar to the old tungsten bulbs you need to look for "warm white" (2700-3000k if they give a number). I have had the daylight ones & they're horrible in a house 
The only caveat is that you can't always do a straight swap of LED for halogen - it depends on the fitments.