The last two years won't do ya any good. Ya need to know what you've currently been spending on an average the last 3 or 4 months. You might've had a huge order 2 years ago and/or some other oddball scenario. You need to figure out, if it's increasing currently. If you farm out banners/wraps or other printed media 2 days a week, keep doing it. 3 is the 'on the fence' part. Anything over 3 days, should afford you enough to get a 54" printer and a 60" laminator. Remember, ya need the real estate to set up a laminator work station, even if it's on wheels.
When we were in the market for a flatbed, we couldn't quite do it, although we had almost enough work for it. A job came along that not only paid for the unit, but all the cost of setting it up, buying ALL the media for that particular job and we still made a nice profit. Not all jobs will yield that kinda turnaround, but if you can count on 3 days a week of work, that should be a payment on those two machines.
The other part is..... once ya have it, you'll promote the livin' sh!t out of it and drum up even more work.
This is all based upon the fact that you are not independently wealthy and just doing it for fun...............