I use a small MarkBass combo (the CMD121P to be precise). I really like the sound, both with double bass and my bass guitars (which include a Jazz bass). It has a clear yet warm sound, plenty of power and is very portable. I've seen them second-hand on BC for around £500 and would recommend looking on the classifieds here - you get so much more for your money by buying used.
Lots of people like Ampeg too of course but I prefer my MarkBass. I've not tried an AER Bass amp but my missus has an acoustic combo of theirs and it's first rate but pricey as you point out. Other options to explore might include Genz-Benz [url="http://www.bassdirect.co.uk/bass_guitar_specialists/Genz_Benz_Contour_Combos_210,_115.html"]http://www.bassdirect.co.uk/bass_guitar_specialists/Genz_Benz_Contour_Combos_210,_115.html[/url]
I don't know any good bass shops in Manchester but when you are next in London, take a trip to The Gallery in Camden and try a few out. At the end of the day, it's the only way to know what will work for you.
Good luck!