When buying cylinders, MAKE sure you can exchange them for full ones where you bought them and the place has been around for a while. Also make sure that you actually own them and they aren't a lifetime(15 year lease). I say this because a place here used to call a 15 year lease lifetime. That company was bought out by a larger welding supply and the leases were no longer honored.
When getting prices make sure they are for filled cylinders and not empty cylinders. You might think you're getting a deal but then when you get them filled, there's another $200 or so added to the cost. Prices here are: 75 cu. ft. acetylene and 122 cu. ft. oxygen about $570 full, 150 acetylene and 244 oxygen about $740 full. A decent basic torch set starts at about $200 and a contractor set with a decent size rosebud (heating tip) is around $360. A top of the line set with several welding tips, heavy duty regulators and a rosebud is going to be $500/600 and more but you don't need that. Some basic sets come with a rosebud but it's so small you could heat just as much by using a larger tip in the cutting torch. You do need a larger acetylene cylinder with a big rosebud though. For comparison, cylinder leases are about $96/yr for each cylinder, so by the 3rd year lease you would be saving money with the outright purchase.
I would suggest a 75/122 combination and check with the welding supply if you can upgrade to larger cylinders in the future and just pay the difference in cylinder cost and cost of the larger fill. I'd go with a torch set in the $275 to $375 range depending on what you need. Get a name brand torch and make sure they have cutting and welding tips in stock as well as specialty tips for rivet cutting, gouging etc.Ask for a deal if you're buying cylinders and the torch set at the same time. You're estimate is right on the money. Another thing that could save you a little money when you need refills is to set up a charge account with the welding supply. Then you can negotiate a little better deal on refills. You can still pay at the time of purchase if you wish but your negotiated prices will be set up in the computer. Even if they give you a few bucks off of refills, it still saves you some money.