First the economics how much does it cost to run a 50W light bulb?
Easy: 50/1000*4*365 * Cost_per_Kwh = £7.30 @ 10p per Kwh
Assuming you run your light bulb for 4 hours a day 365 days a year, as it’s darker in the winter you’ll use more and probably a bit less in the summer. So when you buy the cheapest bulb usually about £1 from the supermarket you are also committing your self to spending £7.50 every year to run the bulb.
I just bought 2 chandeliers from Homebase with 25W G9 bulbs and connected them to dimmable sockets.
My usual procedure for buying bulbs is to buy one and test it out, the test bulb proved ok so I ordered 9 more. It seems to me that Filament bulbs are just a wire which gets hot, while LED bulbs have a pedigree, descended from modern electronics which demands quite fussy voltages and probably direct current which requires all LED bulbs to pack in a really small transformer. My experience with my 9 bulbs extra bulbs, which rapidly turned in 8 extra bulbs when on went bang when I plugged it in, is that I could only find 7 which would work together with the dimmer system and not cause a noticeable annoying flash.
I think LED light bulbs are poised to take off in a big way soon, I wouldn’t recommend the bulbs I bought for my chandeliers, but I haven’t taken them out, I’m just disappointed with them. But I think there is a better way to power our lights. It seems to me having one transformer per bulb is missing a trick. The manufactures are forced to put in the cheapest transformer they can buy, this I’m sure leads to the bulb flashing problems. A better solution would be to have your transformer circuit in the light switch, so your bulb is fed electricity from the mains in a stable way, you could then make smaller and cheaper bulbs. You of course then cannot run LED lights with filament bulbs.
Back to economics my LED bulbs should save me £25 a year, they cost £84 and will require £5 year to run. So breakeven for them is around 3 years. If the price of electricity goes up even less.