all my jersey and auto cards I keep in toploaders, I keep all my Exquisite in 1 touch magnetics, then I have a good bit of my serial numbered stuff of RCs in toploaders as well...for 'base' cards, I use 5000 count white boxes known as 'monster' boxes here in the states...
in 'displaying' your PC you need to be aware of lighting situations because many of the sticker autos will fade fast, as will the actual card color, so that is something to be aware of...
as for buying toploaders, yeah, they aren't cheap, not sure what your conversion rate is, but around $60 USD will get you a case of 1000 toploaders here in the states, and the bigger the thickness the more expensive it gets, I think I pay around $4 for 10 180pt cases...
not sure how they are with international shipping and such, but sites I typically buy my supplies from are
www.blowoutcards.com
www.dacw.com
then I know people use Atlanta Sports Cards (no clue what their site is as I refuse to use them after they canceled an order of mine probably 8 years ago)...
I believe most toploaders come from China, so unless France doesn't allow trade with China, you might be able to find a better way to get them than ordering from the US, because I know that international shipping gets expensive quick, and a case of toploaders goes for what 23 pounds or so (10 kilos for you metric system folks)...like here in the states, shipping to Canada there is a HUGE price jump going from under 4 pounds of weight to over 4 pounds...to where it is almost cheaper to break down a weighty shipment into multiple boxes, as it jumps from like $20 to $30 when you cross that 4 pound mark, 3.99 pounds is like $20 and 4.01 pounds is like $30 if I recall correctly...
the 9 pocket pages is probably the cheapest way to go, but you need to be careful as some cards begin to stick after awhile, I know this is common with products like Upper Deck Encore and even regular Upper Deck in the mid 90s, so you probably want to put them in a penny sleeve before sticking them in a page, especially if there is a chance of mid level or higher humidity, as you can lose some surface, plus the pages aren't the softest plastic and can scratch the surface of many high gloss issues, especially your Topps Chrome Refractor stuff, but even regular Chromes are easily scratched without a penny sleeve...
hopefully that helps with some of your issues...
and yeah, counting my PC in with the stuff that I buy to resell, I have around 4500 autos, 1000 relics, 600 Exquisite, 1200 SP Authentic serial numbered RCs...that is a LOT of cases...the 120pt magnetics are over $1 each now when bought in bulk...so I wouldn't be shocked if I have over $1500 tied up in toploaders and assorted holders
