There are tons of storage options around Disney (especially within a 1 hr radius). Offhand, I know that both Thousand Trails Orlando and Lake Magic have outdoor storage and I think it's around $90 / month. If you store it at TTO, be very careful where you park it as the storage area is essentially grass on sand and we got stuck last year and a few days after we were towed out, I noticed another RV being towed out of the sand but as long as you are careful about where you park, it shouldn't be a problem (my problem is that I parked it going uphill (RWD) and I didn't notice my wheels were spinning which got me stuck). If you get closer to Orlando, I think the going price for outdoor storage might be more like $100-120/month. I think covered parking is likely at least twice the price of open and indoor is likely twice the price of covered (my personal opinion is that the RV is made to be outside but I don't have a particularly expensive RV either ...). If you don't mind going 30-45 minutes away from Disney, I suspect you can probably find outdoor storage for $50/month. I think you might even be able to find it around that price in Sanford (which isn't nearly as remote as some other areas (e.g. parking to the West of Orlando-Kissimmee))
We've been storing it in the Tampa-Clearwater area for years (because that's were we like to fly) but will be storing it near Orlando this year as we have more / cheaper flight options to the Orlando area. We actually fly to both Sanford (SFB) and Orlando Intl (MCO) so will be storing it between those two as I'd rather be closer to the airport.