If you do the math, there isn't any way that a park is making much money even charging $475 a month. Say it has 100 sites. That's $47,500 a month. Figure 4 months MAX, that a gross of $190,000. That has to pay the utilities other than electric, pay all the labor (front desk, lot maintenance, cleaning restrooms and office etc.) Has to pay the electric for all the common areas. Has to pay for repairs, upgrades etc. Has to pay for supplies (office, pool chemicals and other assorted items) Has to pay advertising, has to pay taxes (property tax in Texas is very high) and then also make a return on investment for the owner. None of those costs have stayed stagnant over the years.
I suppose the park could have been progressive and raised rates $20 or $25 dollars a year, but like many businesses, they probably got complacent and kept things the same for a number of years and now has to play catch up. The fact is not too many people are going to change their winter plans over a net price increase of $400.00 for the season. ON EDIT: In the US we have to pay all our bills in US Dollars. The valuation of foreign currency isn't something our creditors consider. The Canadian Dollar falling 25% doesn't cause our costs to drop. The fact of the matter is with gas prices falling, you can probably recoup nearly the cost of the price increase in your fuel savings for the trip.