@Guillermo Rozenblat this is not as hard a decision as it looks. Let's break it down.
1. You bought a house in Austin that you planned on living in it. A brand new built at that! Great, you locked in a price in October and almost a year later it will be move in ready.
2. Due to new circumstances, you no longer want to live in Austin, what to do, lose 6k walk away, buy it and rent it or buy and sell it.
Before I give you my opinion ask yourself this question. If I were to buy a property for the sole benefit of renting it out, would I buy a new SFH new built? My answer to that is absolutely not. As you are finding out it is harder to cash flow positive on a new built SFH than an existing small multifamily duplex. Not to say in the Austin metro that you would be positive with a duplex but you would likely have a better chance to be positive with a duplex. The other issues are many when it comes to renting a new built home. You are getting a very nice home that renters will definitely abuse. Are you ready for that. Smaller duplex units are easier to keep up and thus rented. It is far easier to find two, $1200 renters than one $2400 renter. Lastly you might have HOA issues as well, don't really know, but since renters are not overly concerned with HOA rules you might be having some issues with the HOA. Sounds like you are not very experienced with renting to tenants and that is a whole new can of worms at this point, especially if you plan on moving overseas. I would definitely rule out renting.
Now, do we lose the 6k or buy and sell. Usually this is an easy decision as most cases trying to sell a brand new built and compete with builders on their own product is very difficult to due............unless the market has blown up from the time the contract was executed and the acquire time has experience a huge appreciation. In your case you might be lucky that this is the case. The easy thing to do is just walk with the 6k loss, but if I had significantly more to gain by selling then I would sell.
You might not even half to wait for the house to be built. You might start looking for a buyer now. I don't know if the builder can prevent you from marketing the contract but if allowed I would start investigating sell it and walking away with some extra $$$. If not start marketing 45 days out from expected closing and sell if you reasonably expect to make a profit. If after trying to sell it becomes a bigger issue then before the house is finished give up the 6k and walk away. We are entering a new phase with this market and it might not be as bad as some people are predicting or it could be worse but you hold he options to either buy and sell or walk away. Make the decision that nets you the most money or if you are a non-hassle person take the 6k loss and walk. In the big scheme of things 6k loss is not a big deal.
Remember to include the cost of selling which includes the cost of getting your loan AND the cost of selling too. You probably need at least 10% more on the sell side to break even. Above that it may be best to buy and sell, below that I would walk away. Good luck!