In one word, yes! The internet is the most effective marketing tools in existance nowadays, have the capability of reaching far more people than any leaflet drop or advertisement in the local paper ever will.
Should you produce your own website?
It all depends on your skills, if you have the ability to produce a site that looks good, then go ahead, it will save you money and will work wonders as a marketing tool. However if your skills are limited or non-existant then we'd say no. Why? No, not because we want your money (although we don't mind if you want to give it to us...), because if your site doesn't have a professional look to it, then it is going to reflect badly on your company's image.