I've got one of these you can have for £4 posted (First Class Packet) - payment via Paypal.
However, you need to know that those things could be a nightmare to remove - the Regina Extra was the worst things ever created when it came to getting it off the wheel! The notched fitting into which the tool fits disintegrates with ease, and the tool therefore needs to be clamped very
securely onto the hub axle (QR skewer, e.g.). These were the freewheels that resulted in manufacturers moving to splined tools...
Even if you are really careful it's still possible to destroy the dogs with the tool - I've seen that raised section peeled right back until there's nothing left! If you do this the freewheel is obviously finished anyway. My suggestion would therefore be that you dismantle the freewheel:
Knock the cover plate off - the two holes turn clockwise to undo (LH thread)
Holding the freewheel over a large bowl or similar pull the bit with the sprockets on it off of the wheel. Tiny bearings will shower everywhere (hopefully into the bowl...), and two pawls plus their leaf springs will probably also fall out.
The fitting for the pawls can be clamped into a vice; turn the wheel to remove the remaining bit of the freewheel.
Personally, I'd then replace the freewheel with a modern Shimano or similar.
However, it's perfectly possible to rebuild the freewheel. It's not an easy job, though. Fix the bearings in place with grease (not too much, or your freewheel will work both ways...), place the pawls / springs in place and hold them flush by wrapping cotton thread right around the freewheel boss and over the pawls, and replace the bit with the sprockets on it. It's much easier to explain this than it is to do it; you need about seven or eight pairs of hands and considerable precision to avoid another display of exploding balls.
PM me if, after reading all this, you still want the remover!