Tools
The more tools the better, and we all want to be Tool Time Tim. However the following is Doug's advice about what is worth spending money on.
Get a decent (chemical and dust) mask and spent at least €50 on it. You need this if you want to spay paint or you could end up poisoned without out it. The more you wear it the less change you will end up with lung caner. They are horrible to wear so get a good one and put it one when you sweep up, do a lot of sanding or spay paint.
A compressor and spray gun will save a lot of sanding when doing paint jobs. There are cheap in most DIY stores and the more you spend the better. However €200 is the minimum I would spend.
A vacuum pump dramatically improves the quality of your layup. They reduce air bubbles in the lamination and remove excess resin. They add a lot of consumable costs to the layup but I think it is worth it. I got one from ebay for €200 after a lot of bidding effort. You can get then cheaper if you are a better ebay bidder.
Get a big box of disposable Latext rubber gloves. These are cheap and mean that you get less epoxy on your skin and a soon as things get messy get rid of the gloves and put on a new pair. This will improve the quality of your work by helping to avoid the epoxy everywhere mess.
A set of digital scales for measuring resin and paint hardner ratios are worth spending ~€25 euros on. Do not use your Mums they will get covered in paint and resin. They should have an accuracy of +/- 1 gram and will make mixing up resin more accurate than the stick method. The quality of the ratio and how well you mix it has an effect on the structural quality of your work.
Get and use lots of kitchen roll to keep tools and work clean. Use aceton to clean tools after you have finished. Consumables cost but are nessasary for good results. If you keep your work clean it will save time (and dust) sanding crap off it later.
Always be on the look out for stuff you can use. Tin cans are great cheap mixing pots. Lolypop sticks are great for mixing and filleting. Broken carbon rackets are great for building bits. Broken masts are great for trollys and wing bars. Old furnicture provides wood for frames and building gigs...
Do not waste money on electrical sanders. They are loud, kick up loads of dust, use expensive sandpaper and insensitive. A good block roll of sand paper and elbow greasse is all you need. If you spend too long sanding then you did not get the last job right. The less filler and sanding the less weight, time and dust.