Hi Nino
I got the 50's static caps from PBR and they were really quite cheap I thought at $5 each.  The Space Invaders branded caps cost me USD$18 for the set of 3 from memory from a guy in the US who is using the same heatstamp method as the original (there's a youtube video of the process he uses).  From memory it was Classic Arcades Inc.  I took a pic of the old vs new caps).  You will note the pic on the left is the original cap that is burnt from the globe, and the repro one on the right looks superb.  They really look great and I was happy to spend $18 on that set.  I also got the insert decal sheet and apron decal from those guys.






I had read previously that it was extremely hard to find these anywhere and NOS ones were going for crazy prices.  I stumbled on these ones on Ebay.  I also got the custom drop targets (pics below) that I think look great.  Again they are hot stamped