I would lean towards either a drum/disc mower, or at least a haybine (sickle with feed tines and conditioner rolls). I mowed with a plain sickle for years and did it at 2 mph, haybine doubled my speed. You could handle a 9' easy enough. a 5' or 6' disc/drum would also be good, faster than the haybine but not as wide so a wash there in my opinion. Sickle, weather it has the rolls or not is pretty finicky to get adjusted properly, once you get it they are great. Disc/drum is almost foolproof. Also out there in my area are a few flail mower conditioners, great mowers but they like there HP.
Small square balers are cheaper because most farmers don't use them for production haying anymore, most have gone to big bales round or square. A baler requires a lot of care and maintenance both round and square, lots of moving parts. If it works well, keep it lubricated, store it under cover and clean it out when not in use and it will last a long time. If you are handy they are not too complicated, just a lot of parts timed to work together. Rounds are more subject to wear mostly because they are production balers, most of them have seen a lot of hay. The bales are heavy, belts stretch and wear, bearings fail, a lot of the older ones were not designed for silage and people used them anyway, even for a season or two this is hard on them. Either way I would ask to see the baler working before I spent too much money on it, even if you have to bring a bunch of hay and spread it out by hand to bale it., worth the effort in my opinion.
Just my 2 cents, probably worth a penny.