Office Chair?

the last couple I bought for use at home came in a box un-assembled. so just go to any of the big box stores or the office supply chains, find the one you like and take it home in a box. If box won't fit through door, then open and take it in piece at a time. assemble inside.

I have done this for several storage cabinets. I have bought and carried them in piece at a time, as the box was too heavy for me.

We replaced our uncomfortable dinning chairs with office chairs with adjustable seats and backs and height. We tether them to the table when travelling. Works for us.

Costco usually has 2-3 office chairs (secretarial and executive styles) at a good price. The only issue will be securing it for travel - either lash it or lay it down.

I use a cheap secretarial chair and find it to be comfortable for my use at the computer. Since it is on rollers, we lay it down for travel.
Russ

I assume you're looking at a chair to wide/deep to slide through the doorway. Most chairs can be disassembled - and that may be necessary in your case. Also, feeding them into the door opening "sideways" and twisting as they come in might also be a possibility. Worst comes to worst, perhaps a smaller chair would be needed.

Good luck.