Keep in mind that printing a full-size item on even a 200x200x120mm already takes more than a whole day. I can't imagine you wanting to make prints that take a few days. If you ever get an error during the print, you might have waited a few days for it to finish for nothing.
That said, I think theres A4-sized heatbeds, haven't seen them bigger. And I definitely haven't seen kits that big.