Super stiff rackets are usually highend rackets and don't really sit within the lower or mid price ranges,at least this goes for the big 3 brands. Other options could be LN's Tectonic 9 or Victor's (original) Ryugua. But both also rather expensive. Or look for Forza rackets. Some of these are really stiff too and should be cheaper than the big 3.
It might be easier searching online retailers to see what stiff racquets are available. 2 of the 3 big uk online sellers let you filter via hi flex, mid flex, or stiff / extra stiff.
gosen may have a few offerings in those specs. you can check them out on shuttlehouse. may be a good time to buy from them when the yen is weak...unless the prices have been adjusted already.
Consider Astrox 100 Game and Astrox 99 Play/Game. Older rackets to consider if you can find them are the Astrox 88D (OG), Thruster K 9900, Thruster K Falcon (blue), Voltric Force and Voltric 50 etune.