As someone who will be applying for a residency permit in the near future, I for one would tend to seek help.
I have read previous idiots guide type lists of application procedures and fully understand where, what, when and how to go about it, but at present I still reckon the £60-70 may be a worthwhile outlay if it simplifies things for me.
I would be interested to read of anybody who has went through the procedure using professional assistance and thought that it not worthwhile.