It's not all that cheap here anymore either.  

If I was 25 years younger you could call me neighbor I would move there in a heart beat as bigger cities go its a great city to work in.. permits dead cheap.. quick and you pretty much know where you stand once you know the rules. those 7 lots I did on Oak and Buist I got them subdivided in a matter of 100 days or so.. that would have been 2 years and 50k in my market here in Portlandia.

I wonder whether it is possible for me to buy a mobile home with cheap price, install that and sell it as a regular house ($110-$150K).

It seems that vacant land is really cheap compared to home values, especially downtown.

Starting to look for deals anyway and trying to find cheap deals that can be rented for the highest amount - the only possible deals in my opinion.I know I'm young, but I don't see how my dream is even possible.

The problems are 1)markets where appreciation above inflation is sustained over decades is exceedingly rare (but they do exist), 2)in these type of markets your initial cash flow will be much lower (but not in the long run with rent increases) as compared to a market with high initial cash flow and no appreciation (negative appreciation after inflation), and 3)markets with long term appreciation by definition are not cheap so you will need some capital to get started.

you can use a heat treatment but the best seems to be a ultraviolet light disinfectorit kills everything and that way you are not using chemicals or have any missesthese units you can rent they are not cheap but it does the job and it saves you from the exterminator feesthey are called true d uvthey use them in health care and hospitalsenjoy

House hack into a 2-4 unit to live super cheap or for free to save even more for the next buy and hold. 

The homeowner/investor wants a service as cheap as possible, at the same time as the contractor wants to accomplish the service as quickly and efficiently as possible.

Sounds like you are rediscovering the truth in that old axiom: Fast, Quality, Cheap ... pick two.