I have been wanting to mod one of my guitars...but then thought, Hey I'm gonna build my own...Is this a good idea? How much would it cost ?
The first guitar is going to cost you more in tools than materials. If you are serious about making a guitar i recommend buying a book on it. Melvyn hiscocks "make your own electric guitar" is an ecellent book.

The cost depends on what quilty of parts you want to use and what tools you have access to.
you could always use warmoth. but have you though this through thoroughly do you have access to the tools needed to create a guitar.
See if you can rent or borrow the tools, or else the tools will cost more than the guitar.
how much will it cost? if you have tools, anywhere from £50-£2,000, (around $100-$4,000 US) :P

Just a rough guideline lol
umm, if you have the $4000 maximum, then you can buy all the tools, and then you will not have to rent them in the future, bandsaws and belt sanders will probably be the most expensive tools needed
what like buy one from warmoth, it wont be that expensive than besides buy a body, you will either buy/build a neck, then electronics and pickups, not as expensive as building one from scartch but its a good idea to do for your first
It wont give you the hang of wood-working if you order a pre cut one, also making your own neck is sexy.
Yeah, but seeing as I'm a noob all that you lot have said (besides the link) means nothing to me WHATSOEVER...Oh, by the way...with the warmoth thing...I'm english...
You dont' need a bandsaw, a jigsaw with a couple sharp blades will suffice. A router is a definate, a drill with a couple different sized bits and such will be needed, an orbital sander, a planer, and lots of sandpaper. And maybe a drill press.
^ +1

The power tools i use most are my router and drillpress. A bandsaw is a luxury, it is not nessasary.