Hi Yael
We had a wooden chair for DS and I absolutely loved it and have nearly killed DP as he left it out in the carport in the rain for a week (i didn't know it was there) and now it is covered in mildew so i have had to get a new one for DD - which by the way was an Ikea one which is almost as good even though its a plastic and has leg holes so no chance of slipping out but no lining.
Anyway to make the wooden one more comfy i put a cushion with ties on it and in all honesty i never had a harness for it i never left DS in it for longer than a meal and never walked away from him when he was in there. Also the tray went right in close to his tummy which made it almost impossible for he to pull himself up.
I did see one on ebay a few weeks ago that went for $40-50 that was a David Jones wooden chair so pretty reasonable.
IKWYM about the lining and food my mum had one of those types as a spare and it was feral would never use one again.
HTH