It's such a hard question as a baby can cost as much or as little as you like. In the early days it would save you money if you breastfeed, unless you are on any benefits and can get free formula. The only other expense is nappies which are expensive. You can get washable ones now which cost upfront but then thats it until the baby grows a bit.
You will probably find that once friends and family find out they will start donating things to you like clothes, cots, pushchairs etc. Babygrows etc are pretty cheap nowadays so maybe but the odd one or two every so often during the rest of your pregnancy, as with vests and cardi's which you will need from the early days.
A lot of people spend loads on equipment which you don't really need, you can make do without things like changing mats and top and tail bowls by using a towel and any plastic dish.
Let us know how you get on.
Much love