Your question is too generic and carries no details about what kind of business you are looking or and what niche you want to target but if you would like to sell the business when it matures (or nearly matures), better go for a single product business as it will have less complications and an easier exit strategy for you.

For starters I think this is an awesome business model. I have been using a virtual assistant out of the Philippines through UpWork for the last 9 months. My first suggestion would be to try it for yourself.. Get a feel for the business model and maybe see what can be tweaked or modified to provide a better experience for the customer. After doing that THEN you should consider a good marketing strategy before entering. I looked at 12 different services for virtual assistants before I settled on UpWork, so whatever you build is going to need some good exposure and SEO!

Hi there, There are so many directions you can go, however, I would suggest you do some due diligence around a few areas:
1) what would someone be willing to buy
2) what would they be willing to pay for it
3) what would make it sellable

If you can clearly answer those questions, you'll have a better idea of what your business will want to sell.

Also, I'd like to suggest you rethink your numbers. Given what it will take in investment of time and money to create something that is sellable, you'll certainly want more than $35,000 for it.