I thgink that you may be struggling to find a sat nav for that sort of money. The cheapest I could find is for around £270. Check out the link below:
http://www.pdamods.com/proddetail.as...TIP1710&cat=95
I know that you stated you won't require the PDA part but the cheapest Tomtom 300 I could find for you was at £370 (a bit of a difference eh??). If you are interested in this check it out here:
http://www.maplin.co.uk/Free_UK_Deli...700__45915.htm
Your other alternative is to go for a second hand unit. There is a section in this forum called Marketplace where people sell their second hand units when they upgrade. I can't be sure but I thought I saw a tomtom go 300 for £250 there a little while back (bargain depending on condition). You could always contact the seller via PM and request some pictures.
Good luck