There is more to dress boots than just the really hard dressage ones. For general english riding it is possible (and usually easiest) to just get field boots without the laces, usually considered a type of dress boot. Also, to make it easier to get them on and off it is possible to get ones with zippers.
If you are looking for a relatively cheap pair of boots that look good in both the dressage and hunter/jumper rings then Equi-comfort makes a wonderful boot that fits well and is comparatively durable for other boots in it's price bracket.
Also, imo field boots are ugly in the dressage ring. Those flappy things are just a huge distraction and draw too much attention to a floppy leg. If you are leaning towards doing more hunters or jumpers then go for them, but otherwise general purpose dress boots are much more cost efficient in the long run.