Elegoo has multiple listings at different prices so hopefully I've found the cheapest for each model.
Neptune 4 Pro $283.99 225x225x265mm build area - https://www.ebay.com.au/itm/395014872018
Neptune 4 Plus $359.19 320x320x385mm build area - https://www.ebay.com.au/itm/394727782696 (select correct model from dropdown.)
Neptune 4 Max $452.79 420x420x480mm build area - https://www.ebay.com.au/itm/395122342367
Note: At time of writing only 5 available on the above Plus listing. Next cheapest is https://www.ebay.com.au/itm/395040969123 @ $393.59
All models run Klipper and are capable of nozzle temps up to 300C and print speeds up to 500mm/s. However, these are not Bambus. You won't get an out of box and ready to print machine, some prior experience is definitely going to help otherwise a bit of learning is needed first.
They also seem to be hit and miss, some people get great results out of them while others give up and end up returning them (whether that prior experience comes into it I dont know) As far as I've seen at least Elegoo are pretty good with support sending spare parts when required. I've had a Plus for a few months (bought for a little over $400 at the time) and while I haven't had much time to give it a good workout so far I'm liking it and it's giving decent results. There are very active FB groups and Discord dedicated to these printers which can be very helpful.
Just don't underestimate the space required for the Plus and especially Max machines.
Awesome pricing.
I’m waiting on my OrangeStorm Giga to arrive