If you include unlimited editions, then without any doubts becoming an astronaut is way more realistic. I’ve only seen two unlimited edition L1 cards to begin with, which can be found here in this thread (which also contains some discussions about how those UED L1 cards might have been released). Before that I and many other collectors who’ve been on the lookout for these cards on a daily basis for multiple years haven’t seen a single unlimited edition L1 card.
I’ve said a few months back that I most likely would be able to add the SNAP Photo Contest 1999 card, of which only 20 exists, and the last one sold (a.f.a.i.k.) was in 2005 for 8,500 USD - in today’s market I wouldn’t be surprised if it would be able to fetch 35-55k USD (which I don’t even have), before getting an unlimited edition L1 Pikachu in Reverse Holo. The unlimited edition L1 Pikachus, E1 Pikachu, and WCP Seviper and Battle Frontier cards are a few of the last cards to complete my collections…
As for unlimited edition L2 and L3, that is possible, but also very hard. I have a few of them myself, and I know @supersaiyanampharos used to collect them since I sold him my duplicated copies once (although he isn’t very active anymore, so I doubt he still collects). (I just checked his collection thread, but the pictures seem to be broken at the L2 unlimited edition posts unfortunately… 
).
1st edition L1/L2/L3 shouldn’t be too hard, but if you’re going for unlimited as well, I wish you the best of luck with the L2 and L3; and I doubt you’ll be able to find more than 5 cards in 5 years time for the L1. 
But if you find even a single UED L1 card, make sure to share it here on the forum. And if it’s a Pikachu, I will buy it from you by any means necessary, haha.
Greetz,
Quuador