Nerja as a home base for 1-2 weeks?

That would be like....

"Hey, buddy, I have this timeshare in New York that I need to use; I gotta pay $450 for it for a month...I know you really want to visit LA and Miami, so why don't you take it off my hands and it's a win-win for us both! Just use it while you do your short trips to LA and Miami, it'll be great! Thanks, pal!!!"

You get to pay for your actual accommodations in Barcelona, which you would have to pay for anyway, and you pay your buddy for the unused time-share in Nerja. If you do trips to Madrid, Lisbon and Morocco, you get to pay for your accommodations there, too - which you would have to pay for anyway.

Ask yourself this: if your friend wasn't offering you this oh-so-generous deal, would you want to pay $450 for two weeks in a condo in Nerja? That's really the only thing to focus on - the rest is misdirection.

What David said. And:

Morocco's a great place if you have a fair amount of time and can see places like Fes and Marrakech. It is not a good destination from Nerja; it will take the better part of three days just to get to Tangier for part of a day, and then you'll just be in Tangier. Don't do it.

Portugal and Spain are surprisingly poorly connected by ground transportation. You'll waste a lot of time trying to get to Portugal from Nerja.

The top destinations in southern Spain are Cordoba, Seville and Granada. Only Granada is close enough to Nerja to be a really viable day-trip, and most people would prefer to spend a couple of nights there to enjoy more of the city than just the Alhambra.

What time of year are you thinking of making this trip? Hotel rooms in much of Spain can be relatively inexpensive outside of Barcelona, Madrid and San Sebastian. (I haven't been to Andalucía recently so am not sure about it, and of course the time of year matters.) You could spend a lot of nights in perfectly OK (clean, decently located, but possibly rather small) hotel rooms for $450.

Price - 450USD might be a good price even for 10 nights depending on what you're getting (I don't know what a "condo" is), and when you're coming. If its a villa with pool close to the beach and in Summer then 45USD per night, say about €40, is a great price. If its a small bed-sitter flat away from the centre in February then you can find cheaper options.

Location - Nerja isn't great for the other places you mention. You can't day-trip to Lisbon or Morocco from there (well, perhaps, in theory you can, but certainly not sensibly). You could see some of eastern Andalucia by public transport (e.g. Granada, Malaga) and more by car (e.g. Cabo de Gata). If you put in long days you could visit Sevilla or Lorca, but for a day-trip these would be over six hours of driving there and back, so wouldn't appeal to many of us. How much do you plan to actually use it as a home-base to explore and how much do you intend to simply have a beach holiday?

Reading (or misreading?), between the lines, it seems to me that a Nerja base isn't really what you are looking for since you want to travel around and see sights in various towns. But, equally, millions of people do happily take their holidays along the coast every year, just not with the intent of widely touring Spain (let alone Portugal). Some of us even take jobs here and temporarily move! So it depends what your priority for this trip is.

We spent about $550 USD total on Airbnb's for our stays the following cities: 2N Cordoba, 2N Granada, 2N Nerja, 1N Ronda, and 2N Seville. A bit more than you are saying for your base in Nerja, but I have to agree with the others that none of these towns are good as day trips from Nerja. You would be spending your whole day just getting to and from the cities by train or bus.

Now, there may be other nearby cities that would be good as day trips if you spent, say, one week in Nerja. There is Frigiliana, the Sierra de Tejeda natural park, , other nearby towns with beaches, Malaga (although most would probably say to use Malaga as a base rather than a day trip). But I think it would be a shame to visit southern Spain and not see Granada, Seville, etc.

Whatever you decide, have fun in Spain - it is lovely!