Car won't start please help

My brother bought a 1994 XJ6 a few years ago and was driving it part time it ran fine started fine,and recently the battery died so he took one out of his other car to try and sell the jag but when he went to work it started as usual when he went to go home the car would only turn over so he left it and when he went back to work the next day it started up right away he drove it home parked it and now it won't start just turns over like it isn't getting spark or fuel. We have checked all the fuses they all seem fine. i remember talking to another jag owner that mentioned if there was ever a no start issue it could be the crank position sensor. we pulled it out cleaned it up it didn't look bad but i was wondering if there was a way of testing the sensor before he spends 150 on a new sensor (canadian price). I have been helping him but seems that we are chasing our tails trying to figure this out and if i go to the wrecker and find one how do i know i got a good one or should he just buy a new one.... HE IS TRYING TO SELL THE CAR so he doesn't want to spend alot on it:banghead: