Hi Boobear,
Sorry I haven't replied sooner..................have been out stuffing my face with Sunday Roast

, which will probably show in the scales for Tuesdays medicals but hey ho!!
First of all I just wanted to say that I am by no means an expert on Student visa's, but of course will share our experiences with you!!
In my opinion £799 + vat does seem very high. We have gone with 'This is Australia' (Laura) and she has been brilliant. I also know that Yvonne & Paul are also going with them due to recommendation and I think she is pleased with them so far.
We are paying £400 inclusive of vat. The reason for this is that if 'this is australia' register you for your course they receive appx £400 from Australian Education Dept for getting them an international student. With this in mind they only charge £400 as they have already received the £400 from Aus Ed (which saves me a few bob so I am happy).
I have to say though that the actual Student Visa is very straightforward and there are too many documents to fill in, so probably wouldn't be too difficult to do yourself. I have found it very useful having an agent that is already in Australia as they are also going to help us with other things as well (housing contacts/Tax file number etc etc).
Hope this helps, but please let me know if you need any other information as it is still fairly fresh in my mind all the forms/fees etc.
Good Luck xxx
Heather