We pad print all day, every day here, but that's really what we built the business on and added screenprinting and signmaking to that.
One of your biggest obstacles in competing with ASI companies is sourcing blanks at a competitive price. The sources are out there, but not usually something you can google up. Most are well hidden secrets, You want places that do wholesale to decorators only, anybody that actually advertises blanks is probably going to price you out of the market.
Pen are not something you should be looking to be competitive with. In fact take a really good look at what any given product is worth to see if you can sell a $0.25 to $1.00 print on it. For instance, golf balls are great as good ones cost several doallars each, golfball tees, not so much, even though both print just fine, nobody wnats a $0.50 print on a $0.01 golfball tee.
The key is to find out who needs the service, whether it be your customers for coffee mugs, key chains, flashlights etc. or manufacturers for OEM (original equipment manufacturers) product printing on the things they manufacturer. Plastic injection molders are a good place to check to see if they need printing services. As are powder coaters and places that do anodizing.
The trick is that people wanting OEM printing will want to be dealing with a pro, not somebody learning the process.
The learning curve is many times tougher than screenprinting.