What is your travel date?
You are quoting prices in dollars, so I think you are looking in the wrong place. If you use the website of the Norwegian rail system (www.vy.no), which you should, the fare will be in the local currency, and it should be the best available for the date and time you choose. The July dates I spot-checked showed a price of NOK 1379 for a single ticket on the 8:23 AM train, including the Flamsbana; at current exchange rates that's just over $130 per person. The problem is that other travelers seem to have already snapped up the bargain-priced LowFare tickets for the Oslo-Myrdal segment. For reasons of weather, non-skiing tourist traffic to Norway is concentrated in just a few months. July is definitely part of the peak period; June would probably be somewhat less expensive--at least it was last year.
On some dates in July the 6:28 AM departure is a lot cheaper than the 8:28 AM departure. No, I wouldn't want to take the early train, either.
Norway is very expensive in general. The Myrdal-Flam (Flamsbana) leg of the trip is on a private, tourist-oriented rail line and is not cheap; I don't think the fares on that train vary. The going rate for the Flamsbana seems to be NOK 470.
In terms of seating, I don't know that you can be sure you'll be facing forward in any case. Train carriages can usually be hooked up facing in either direction, so you may not know until you board. Now, that proviso may not apply in Norway or to the Oslo-Bergen trains in particular. It's true that if you were able to select your own seats, you should be able to avoid sitting at a table, but on the cheap 6:28 AM train I just tested, I wasn't able to select my own seat.