It depends on the satellite! It can range from thousands for smaller pico and cube satellites to billions for some of the larger science based ones. A typical communications or spy satellite might cost £200-300 million pounds! Another things to think about is how much it costs to launch a satellite is the cost of a rocket launch can be hundreds of millions of pounds too and it works out at a ‘price per pound/kg’ for the satellites to be launched. The last few years though have seen a big push to bringing these costs down and making space more accessible for all.
You can probably pick a basic model for just a few million pounds. Of course you have to pay for the launch and that will probably be the same again. Unfortunately everything in space industry is expensive but the cost is coming down. We now have very small satellites called “CubeSats” which are about the size of a shoe box.