What are you waiting for
Its totally legal to print MTG proxies
If that spell or ability later returns the card to the battlefield (as Static Net might, for example), the permanent card will return to the battlefield as a new object with no relation to its previous existence
There is virtually no drawback in playing one copy instead of another basic Forest, which makes Boseiju and the other lands of the same cycle staples in basically every format they are legal in
This Mew card, in particular, is notable for the fact that it is, truly, a water-type Mew thanks to the Delta Species sub-type in which Pokemon types were changed willy-nilly
Theyre all from third-party sellers, not WotC, so exercise some caution just as you would on Amazon when purchasing older decks