New mattress for 14 year old

[MovingtoEssex]

How much should I be looking at spending?
Any suggestions?
Current mattress has done (just about) 12 years.
£135 argos options have good reviews and 100 night comfort guarantee.
Thanks for any suggestions!

IKEA Hovag is consistently well regarded and very well priced. DD 15 has this one and it’s still going great after 3.5 years.

I have Hovag and like it, but it needs a mattress topper.