I run a quick print/copy shop and we offer quick signs, banners, t-shirts, etc. as add-on items.
To start out, you don't need quite that robust a printer as pictured above...a high-end color laser printer ($13,000 or so) can do a lot.
BUT, It's not just the "Printer" you need to consider.
The support equipment & programs for the various items you will be making in-house also have to be purchased.
Cutter, folder, score/perforater, laminator, numbering software or equipment are just a few....PLUS all the paper stocks you need on hand.
EXAMPLE, We just designed & made Table Tents for our local hospital...they were printed full color, one side on white card stock, scored (to fold correctly), laminated, cut down to 4.25" x 14", folded along the scores & taped to form a tent with double faced tape.
Not all jobs are this complicated but you have to be able to "Finish" your product not just print it...even business cards need to be cut down to size.
Sue2