Toyota Repair: 1994 Toyota 4Runner Fuel Leak, toyota 4runner, weekend mechanic

Question
I have a 1994 4Runner, 3.0 V6, with a fuel leak that can easily be seen at the very back of the engine compartment on the fuel injection unit (standing in front of car looking straight ahead). The gas is squirting out, not a small leak.

Vehicle has been very well maintained and ran great until I smelled fuel and looked around and found this leak. I have inspected all fuel lines and the filter, and no leaks found except as described above.

My questions:

Is the likely cause of this leak bad fuel injector o-rings? Could it be something else?
 
Any idea how much it would cost to have this fixed by a professional mechanic?

How difficult is it for a moderately experienced weekend mechanic to replace these o-rings? (I enjoy trying to do this myself, and would like to save money if possible). Are any special tools required?

Do you recommend against trying to repair this myself? If so, why?  

Answer
There is a pipe under the air chamber and a fuel dampener and a cold start injector fuel line you can't see, get your vin number and call your Toyota dealer and ask them to check it for Head gasket recall, if you had it done somewhere else and still have the receipt you can call Toyota and they may reimburse you or don't say anything, haul it up there let them do the head gasket and say your smelling gas also, and I will go ahead and tell you, they will try and sell you everything that is wore out, Timing belt, Idlers, Tensioner, If you have over a 100k and none of this has been done then I would let them do it, they should give you a reduced price because they are already there,the injectors have 3 seals,  get all of them they are not cheap. The only  things that is a ##### is that Egr pipe,lots of wd40 and be carfull they like to brake, the hose in the very back, we take a long pry bar and pick up on it, try not to brake any thing. Take the rad out, lay the power assist pump down, this makes geting everything off easier on the right side. get you a hynes manual or chilton most toy have 10 8  19 17 14 12 27 24 23 35  30 mm nuts & bolts, do it yourself only if you have done this type of work before, hopefully theres a recall, if you don't trust them send me the vin and I will look it up, as this only pays 10.1 hrs under warrnty.