As a marketing tool your website is very important, and it's been my experience that you get what you pay for. This is not the time to be pound-wise and penny foolish. If you put care into your website it projects similar care that you will expend on your clients. That doesn't mean it has to be all bells and whistles, just a decent presentation...
That said, how simple is this change? The site you speak of may look simple, but the guts of it may not be. $1500 for a 'simple' site is a steal; my husband charges US$75 an hour (which is close to AmberHaze's $95 Canadian). Where that $1500 and up comes in is when clients keep adding to 'simple' designs that really aren't.
If you truly want something simple, teach yourself HTML (there are plenty of books out there) or spend a few hundred for Dreamweaver. Or, save yourself time, spend some cash and support your local (or not) designer who may be able to look at it with fresh eyes. It will pay off over time.