There are a lot of fc's on the market around here recently, though most of them are older than that. If there had been any when I bought my boat I would have got one! That is definitely a good price on a 2004. But you do need to consider your potential use. The roll up floor works well, but you can't attach fixed structures to it like you could with a solid section aluminum floor. If you are happy with a tiller set up this is a great vessel. There are sectional aluminum floors available. I occasionally see them on E Bay and Craigslist. I wanted to have a nice seat rather than use the tubes or floor and my forward battery, aluminum gas tank and controls console wouldn't work in a roll up floor boat. Definitely no ski pole without a solid sectional floor! I understand it is hard to know what you want when you start out. But do your best to determine what you will use the boat for the most.
The age and exposure of an inflatable are key. The second used boat you list looks pretty old. Be wary buying very old inflatables. Look carefully at the material, seam edges, the transom and it's bonding to the tubes. I would not buy an old inflatable without filling it with a few inches of water to check for leaks. I bought my 99 zodiac futura with an already separated floor and leaking transom. I was aware of the need for work. I drove a good deal on it! You really have to be methodical and work your way around the boat when inspecting it. The outboard looks pretty old too. That doesn't mean it isn't in good shape. It is good to do a compression check if you can. At least see it run. Pull a plug and use a bore light to look inside the cylinders if you can. Check for leaks in the lower unit. My outboard alone was worth most of what I paid for my Futura with outboard and trailer. You can piece together a set up. But you will usually get the best deal on a used boat, outboard and trailer sold as a package.
Patience! I wanted a sib with speed tubes to improve handling when towing riders. I almost gave up. But I did find what I wanted eventually. Go look at some boats. It helps educate you. Don't buy the first boat you see (unless it rocks!).
Do not waste money on trailers in poor condition. Particularly if you travel to Mexico. Surface rust, electrical shorts or bearing drag can all be fixed, but the trailer must absolutely have structural integrity. I have seen so many boats on the side of the road in the middle of nowhere. I ended up with a nice galvanized Pacific trailer in my deal, then put $500 into it (all SS u bolts on the frame, new tires, 2 spares, new springs, new led lights and repacked the bearings).
In the end my outboard, the trailer, the accessories and all of my equipment are worth waaay more than the hull. So try not to focus solely on the sib if you buy a package deal. It also made me more confident in the deal for my old sib (I could always replace the hull).
Good luck on your search and purchase. Just cruising the bay and fishing is a lot of fun. You really don't have to go huge for that. The level of preparedness required should be proportional to how far away assistance is. That's why jyasaki and I recommend balancing ease of use with safety. As long as remote spots in Mexico are on your list the bar for what is acceptable is raised significantly.