If you can get a secondhand Martin D.15 you'll be very pleased a plain guitar but lovely tone and plenty of volume.... £350 might just get you one but you might be willing to go a little higher once played.

I have been recently impressed with the crafter range of Martin 12 fret copies - look lovely and are great for picking and volume with being tweve fretted dreadnoughts..Crafter - have a look at the TA series


Also have a look at Garrison.. you can get some VERY good deals on these at the moment and they stand up well against amost mid-range guitars

If you are looking Now - this looks like a good January sale!