I would start at the beginning with all of this...
1. OLED is not close. It has been promised for the past 5+ years and is STILL not on the market in any usable large screen format.
2. It will be pricey. If you are struggling with putting together $300 for a 'temporary' display, then forget OLED. It will be $3,000+ at the very least I would expect.
3. OLED will be first generation. It means that for consumers wanting a really good display, at a fair price, with OLED, they should expect it to come no less than 5 years after the technology is brought to the market.
REALITY CHECK - DONE
Now, knowing that you really should be waiting no less than 5 years, and more like 7-8 years on a reasonably priced, high quality, OLED display, why not go ahead and get a decent TV today which will last you those years and will be of some use when (if) you do go to something else?
With that in mind:
1. Why LED? Why not plasma? What type of viewing do you do? What is your viewing distance? Do you have HD? Are you ready to make the change to HD?
2. With a typical viewing distance of 10-12 feet a TV of 50" to 65" diagonal is appropriate. Not just 'recommended', but truly is the right size.
3. I don't care if you think 40" is huge. It isn't. From 10' away, 50" will look very normal to you in about 2 weeks after buying it. If you are sitting at 6 feet, then I can support you buying a 40" class television. The number one complaint by people who buy a new TV is that they wish they had gotten the next larger size. You will simply have to trust that this is accurate information and follow it instead of second guessing it.
4. Plasma will deliver the best looking image on the market today. Unless there is some reason it doesn't work for you, it should be what you are looking at.
5. Stop saving your money for fiction, and put your money towards a quality display. Not Seiki, Emerson, Sanyo, Insignia, Westinghouse, or a long list of cheap imports. Get a Panasonic, a Samsung, a Sharp, or a Sony. Spend the money, and get something good which you will be happy with for years.
6. With a 10' viewing distance and not getting something overly expensive, I would recommend the Panasonic TC-P50ST50 - $1000 shipped to your door.
Amazon.com: Panasonic VIERA TC-P50ST50 50-Inch 1080p 600Hz Full HD 3D Plasma TV: Electronics
Very well rated, well reviewed, and will deliver years of ownership of one of the best images you can have. Yes, a lot more than your current budget, but I would encourage you to change your budget and focus on getting something truly realistic and long term.