For one that performs decently you are looking at £400.
Up-scaling is good for SD DVD's and benefits in colour, blacks and response.
Toshiba do a real affordable player in the sub £200 bracket (name? jfgi I can't be arsed

) but it takes an age to boot and an age to read the initial track lead in on a disc.
The sensible froogle and top choice until they drop in price, unless you are a complete movie buff is to buy an xbox 360 with an HDMI output (either Elite version or a pro with HDMI) and buy an xbox 360 HD DVD player add on, for the Elite you are looking at...£300, £400 with the HD DVD unit the same as a dedicated seperate unit and a pro with the same performance in HD will actually save you £50 to £70.
The xbox 360 HD DVD unit also has the added bonus of being USB 2 and can easily connect to a PC so you can HD DVD ROMS on your puter and movies to.
As for performance, the xbox 360 unit performs better than the Toshiba low end separate I mentioned . Not as good as a movie buffs high end separate but if you don't really know what you are looking for you wouldn't notice the difference anyway. Oh you also have the added boon of having the best games console on the market

Oh almost forgot, if you buy an xbox 360 HD DVD unit before the end of January you will also be able to claim 5 free HD DVD movies from Microsoft, a value of on average of £100 to £125, bargain!