Personally on the electric front (I have no idea about acoustics) I'd recommend a mid-level guitar to start with as the lower-end guitars sound bad enough to be counterproductive, even for a beginner IMO.
You can get a really decent sound out of a £300+ guitar (~$450+ but perhaps pricing varies in the US vs. UK pricing) and it'll be good enough to take you to the point where a more expensive guitar will be worthwhile.
You can get a really decent sound out of a £300+ guitar (~$450+ but perhaps pricing varies in the US vs. UK pricing) and it'll be good enough to take you to the point where a more expensive guitar will be worthwhile.