Gas Leak

I have a gas leak on my 1990 eighty eight royale and it is pretty bad. For a cluple of weeks i have smelled gas when i exited my car and never saw what it was but when i came back to my car there was a puddle of brownish rusty stuff under it. I looked under and saw that an area where like 4 lines run is totally corroded and constantly wet. What will it take to fix it? Or would it just be better to have someone else do it?
How much would it be?

I would leave it to the pros,this way if something goes wrong you have someone to fall back on just make sure they show you what they find before having them fix it.

You'd need to determine if it's the send line or the return line. If it's the return line, you could cut the bad spot out and replace it with a short length of fuel hose. I wouldn't recommend this on the send line because of the pressure it carries. However if you need a quick fix until you can get it done properly, then you can mend the leak the same way.

Its the send line. I took it to a car place and they are replacing it for around 120 and that includes fuel filter and brake lines.

It's always best to replace all of the lines. Here in NY we use a lot of road salt to melt ice and it does a number on steel lines, and the rule of thumb is if you do one you better do them all because the rest are sure to break.