If you can afford to join, then do so. Then talk to every priest you meet and try to trade with him. He'll sell you his gold coin... get as many as you can. They will be very useful in a little bit...
Now, while the priests can drop coins when they die, they don't always do so... but they will always sell them. With the number of these coins that you'll be needing (as few as 16, as many as 66 with no mistakes), it's worth getting them as easily as possible.
And once you've got them all, you can then drop out of the Serpents Guild and do battle with all who think it's a bad idea
