Ranches cost varying amounts of money- it depends on the size you want. Buying a ranch is an investment that I feel is quite worth it. You can build regular windmills for only $250k. Also, there's my personal favorite, the kayak. The kayak will help you get supplies for quests, crafts, and/or simple selling wares to help you make money while saving on boat fair- if you don't have to travel to various places to pick up what you need, you won't have the expenditure of the trip. And there are things you can grow on a ranch that can only be found on ranches, such as wool and Maple Syrup. If you know how to properly utilize a ranch, it can give back to you 10 fold.
I would recommend checking out different ranches, as there are different options you can have on a ranch. Grass or plain? Castle, tree house, or Greek Colosseum or something else? Personally, I prefer grass.
To make sure you don't miss a sub, there's always the option of pinching your pennies, and keeping as much as possible in the bank, until you can afford to get the ranch you want. If you need to take from it to get your next sub, at least it was there to take from instead of already invested in a ranch. Then you can continue to save and scrape until you have made your investment.
Oh, and here's a quick tip. If you haven't already, I would go talk to the GlacierTon Dock Master. For $20k he can give you a non-expiring dock pass to any ranch, whether you own one or not. (You will, however, have to ask if you can go to your ranch for free for once, even if you don't have one. The conversation will lead towards getting that pass, saving even more on transportation when you need to pick up items for a quest you're working on.)
And she is absolutely correct. A bud of mine had once said she could afford a medium ranch, but I advised her to go with tiny because of the costs. 
