I have just resprayed my 90 - Its taken a while to get the finish I wanted but its a bit OTT really - If you use a compressor that will pass 5 - 6 cfm and a half decent gun - Devilbiss do a great gun for 50 odd quid and its great - but you can use something much cheeper and get a good result - using a gravity gun will save paint and reduce over spray so its cleaner - I would work on about 4/5 litres of paint for a nice deep paint finish . less for matt Nato etc .
You will need stuff like panel wipe , sanding stuff , tack cloths etc .
You will also need a mask - Especially if using 2K which is easier to paint - but contains cyanide - Gerson do a mask that will protect from that but is essential - Heat helps as it will aid the chemical reaction in 2K .
I am about £450 in paint etc plus my work .
You can see the results on my thread on here - 90 defender rebuild .
hope that helps a bit