£150 for a man on his own sounds more like it!
Ours charges about £300, but there's Ltd Co returns to do, Corporations tax, then we're both employees of our company so there's our tax and NI and employers NI and he prepares our monthly payslips and at the end of the year our Self Assessments.
Worth his weight in gold - he might not 'save' us much actual cash, but in time and effort he saves us many weeks, plus relieves us of the worry of doing it all.