I think the reason no one is coming forward and speaking to your price is that your definition of a "nice" apartment in a "nice part of Palermo" might be very different than someone else's definition of "nice" and budget needs/constraints. Here is what I saw based on my brief experience, the important factors in determining monthly rental are:
1) location/neighborhood (Puerto Madero-high rent, Almagro-lower rent)
2) age/type of building (high rise, charming historical building, new construction, newly renovated tend to command higher prices)
3) sq footage (the average here for a 1 br is between 45-65sq meters which is tiny by USA standards, but large for here and once you go over 70sq meters price seems to go up exponentially)
4) number of bedrooms (be careful as we looked at 2BRs that were more or less the same sq footage as a 1BR which just meant you had a bunch of tiny rooms but you paid more)
5) amenities in the building (elevator, 24 hr security, laundry, super/admin on-site, gym, pool, lounge area, parking spot etc. will all increase rent)
6) what is included in the monthly rent (does it include expensas (common area charges), electric, water, cable, internet, telephone, maid service, linen service)
7) quality and state of bathroom, kitchen and furniture. (granite counters, quality appliances, furniture is not partical wood)
8) balcony, terrace or garden
9) in high rises, the higher story apts and/or views increase the price
10) close to Subte/public transport
Now none of that was in any priority order, just what came to mind. Not knowing the specifics of your apt. makes it hard to judge if your $800USD per month is a good deal. To help you determine if your price is right, the more items your apartment has from the list above the better. You can also search a short-term rental agency site like Bairesapartments.com - if you enter Palermo and 1 BR and sort by lowest price first you will see that the starting price is about $800USD. Now compare sq ft and amenities and you start getting a better idea. Granted these short-term agencies will be on the higher end of the market due to the commissions the owners have to pay for the listing, most have weekly maid service and price will most likely include everything but telephone in the rent price. So keep all that in mind when judging the rent.
Hope that helps in figuring out if your apt at $800USD is a good price, without knowing much else about your particular place - it at least sounds in the range.