If you’re looking for super low budget, I’ve been pleased with the Jeffers boots. Really attractive, stud closures, and only $52 for the full set.
http://www.jefferspet.com/products/medium-jeffers-tendon-boots
http://www.jefferspet.com/products/medium-jeffers-ankle-boots
If you want something more mid-range with fancier features (like a more breathable, anti-fungal lining and a dilatant fluid strike guard), look into the new line of boots from Majyk Equipe. I was able to see all of their new line at AETA and was super impressed with the materials and construction. The Infinity Series boots would be within your budget.
http://www.ridingwarehouse.com/Majyk_Equipe_Horse_Boots/catpage-MAJYKBOOTS.html?from=900fbp
I like that Majyk really puts a lot of thought into the materials they use… as evidenced by the info on their website: http://www.majykequipe.com/technology2.html