I would strongly recommend a carbon fibre tank as an air source,you can pick up used ones on the classifieds section for £70-£100 but make sure they have at least 2 years test left on them or you could buy a new one for £150-£170 with the full 5 years test and you have piece of mind that it hasn't been mistreated by the previous owner.
As for goggles don't shrimp when it comes to spending money on a set,just remember you will be wearing these for the best part of the day and need to be comfortable and most current premium goggles cost between £40-£100 ...Dye,Proto,JT,Empire,V-Force & Sly make great goggle systems.
There is a certain truth in whats been said in earlier posts,the better the gear (and usually more expensive) you buy now the more money you will save further up the line.
And remember if you see something you like and are unsure if it's a good deal don't be scared to ask.