Ok, here's the deal:
Unless you're moving from SF or NYC, this is probably the most expensive place you've lived. Housing, especially, just costs more around here. Be prepared to spend way more than you ever thought you would for a clean apt that's close to anything.
In order of desirability -
North Arlington, near the metro (East Falls Church to Rosslyn, going West to East): Most desirable. 1br will be well above $1200/mo. Maybe jr 1 br or studios within like a 15 min walk of the metro will fall into your range. See buildings like Potomac Towers (north of the Courthouse metro). Prices go up as you go towards the city, so EFC is cheapest.
North Arlington, elsewhere. Basically anywhere else not realistically walkable to the metro. Usually these are houses, but towards Clarendon, Courthouse, and Rosslyn, you do find some older buildings. These are probably what you're finding, places like Sheffield Court or
Rosslyn Heights. Make sure you don't lease any of these places sight-unseen. Inspect thoroughly and do not settle for seeing an equivalent, make them show you the exact place you will be leasing.
One cheaper place I can recommend is Ballston Park. I doubt they have a website. Half the place is designated affordable housing, but it's actually a decent place. I think a 1br is between 1200 and 1300/mo, 10 min walk to the Ballston metro, if you live on the upper side. Basically, insist on a place close to the intersection of Glebe and Quincy. The place sprawls about half a mile south of that, no longer walkable to the metro.
Arlington divides into N/S at Route 50.
South Arlington. No metro, just busses. Definitely not a younger area, a bit more crime. Try and not live near/on Columbia Pike. Actually, try to avoid the whole south arlington area if you're a 20-something looking for a cool place to live, this won't be your scene.
If you'd like, let me know about the places you've found, and I'll tell you if I've heard anything.