Hi fnym,
The Ultimate Dreams latex hybrid is around the bottom of the budget range where you will find a reasonable amount of latex in a mattress and most similar mattresses would be in a higher price range. Posts # 3 and #4 here includes the lower budget latex or latex hybrid mattresses I’m aware of but the only ones that you are likely to find in lower budget ranges are some of the Ikea hybrids that use mostly synthetic Dunlop latex.
Other than latex … post #4 here includes some of the better lowest budget mattress options I’m aware of.
Phoenix