You will be investing the same time and energy to hire and train staff, outfit the home, locate services, etc., so you might as well go for the highest ROI possible.

If you had a big outfit 24 hour type commercial plumbing company giving you the diagnosis, I'd get another opinion.

But, if you are referring to a group of lessors, the default word to use is always the masculine version. 

With $100k, I'd look to buy a property for around $200-250k (20-25% down) and use the remainder to add extra bedrooms to outfit for a MTR, rent by the room model. 

I think a lot of these outfits make a good deal of their funds by investing this 'float' - IRA money not invested by customers - in other debt or equity investments.  

I usually get better plumbing prices from father and son teams than big outfits.

Before I was using custodian affiliate note investing outfit that did not work out that well for me and did not have returns that justified the risks IMHO.  

Some providers are smaller outfits that have great communication and customer service, but don't have a huge online presence because they're busy doing the actual work that they specialize in.

As far as certification, you can hire an outfit that has bedbug-sniffing dogs.  

You can always go up a level or two but be prepared to pay more for the higher licenses as those are generally larger outfits bidding on bigger jobs.