I've got a poster design that I wish to print. But provided that poster has multiple colors that won't go good for a screen print (further, I would like to restrict screen printing to t-shirts), is there any printing technique that can be used? Please note that, one I'm a DIY guy, and two I don't want the prints on a large scale and hence won't prefer the idea of going for offset printing or some Print-on-Demand printing firm. Please let me know even if there is some inkjet printer or the like that you use that gives out good prints of A3 size at least. Thanks.
Obviously you're limited by the equipment you have at your disposal, but have you considered CMYK screen printing? You will need a 4 color press with precise registration, but it is entirely possible to do: CMYK Screen Printing
Consumer level wide format inkjet printers are available if you're looking to buy one, in my experience Epson is generally regarded as the best quality. Unfortunately, they can get rather pricey: Epson Artisan 1430 Inkjet Printer. This printer can print larger than A3, up to 13" x 19".
If that is out of your price range, I would just consider going to a local print shop and asking for a price quote.
John has a great solution with Epson. Personally I run the Workforce 1100, if you watch Staples they go on sale every other year for 149.99. Last time I bought two. I also picked up BlackMax to print a plate for each CMYK. Do exactly what John's video recommends. In all I think I walked out with a couple hundred bucks in equipment.
EDIT: video on setup with BlackMax
It's really impossible to answer this question without knowing the specifics of your question. But let's start by talking about 'vibrant' and what that means.
I'm going to assume you mean it's a bright, highly saturated color.
Your main options:
Traditional 4-color printing. This is your CMYK process. There's a limit to the range of colors CMYK can make and perhaps isn't going to be as 'vibrant' as you want.
CMYK+more. There are several techniques for printing CMYK inks, plus typically a few additional colors to increase the range of reproducible colors. "Hexachrome" is a popular model which uses a total of 6 colors. Some higher-end ink jet printers also use a 6-color system (Epson makes several).
Spot colors. A 'spot' color is basically any custom mixed color. This is where the truly vibrant colors can come from as you can create colors that fall way outside of CMYK, including metallic ink, fluorescent colors, etc.
So that's the ink-options.
On top of that is actual printing options. You typically will have 3 options: offset printing, screen printing, and digital printing.
Offset printing is the cheapest option for large quantities (per unit cost is lowest).
Screen printing is also cheaper per unit the more you make, but is a viable option for short run posters and t-shirts and the like.
Digital printing (basically commercial ink jet printers) is the more expensive per-unit, but allows you to do very short runs.
So, hopefully some part of that answer will help you. Again, though, without knowing exactly what you mean by 'vibrant' colors, it's really impossible for us to give you specific advice.