I would suggest maybe thinking about getting a camera that has 720p+ video recording capabilities as well as a 3.5mm input jack for a shotgun plug-in microphone (needs to have both the 3.5mm jack and a place on top of it for holding the microphone.)
I know you did say you can't afford a DSLR, but there are some cheap ones that take excellent HD video and it might be worth taking a look at them.
Some good, cheap (HD-Capable) options with a 3.5mm jack and Shotgun support would be:
- Nikon D3200 [$480]
- Nikon D5100 [$520] (I would recommend this particular camera if you wish to have a swivelling screen to see yourself when you record)
- Canon EOS Rebel T3i [$580] (Also has a swivel-screen, and takes slightly smoother video [Colour-wise] as compared to both the D3200 and the D5100)
All three are also fantastic to take pictures with as well, and I highly recommend them for that purpose, too.
Now there's also the option of a camcorder.
These (more often than not) are better suited to take video, and a fair amount of decent ones do support a 3.5mm Shotgun Microphone.
There are some limitations with camcorders, including the inability to buy different lenses for different recording settings, but at the same time, they can be a lot cheaper and a better option if you are ONLY looking to take video. However, sometimes DSLR's produce sharper video quality, so it all depends on which DSLR you purchase or what camcorder you purchase.
I'm more of an expert on DSLR's though, so I'll leave it for someone else to find some decent camcorders with Shotgun Support for the microphone I'm going to suggest.
The best microphone that I can think of that will be both cheap and ideal for recording Tech Reviews and really improving upon the built-in quality of any camera would be the Rode VideoMic or the Rode VideoMic Pro.
Differences between the VideoMic and the VideoMic Pro:
VideoMic [Good Things]:
- Cheaper
- Basically the same audio quality as the Pro
- Lengthy, Bulky (but not too bulky) Cord
VideoMic [Cons]:
- Heavier
- More flimsy on shock mount, causes rubbing of cord on occasion
- Does not include an extra 2oDB boost option
VideoMic
PRO [Good Things]
- Same Audio Quality as VideoMic, so you wouldn't be losing anything there
- Lighter, smaller
- Not flimsy on the shock mount, so no problems with the cord rubbing while recording.
- 20DB Audio Boost Option. This allows for a more dynamic sound range, which is ideal for certain recording settings. The Boost option does not seem to be too bad indoors when it comes to extra noise pickup (hissing, crackling, etc..), so that's always a plus.
VideoMic
PRO [Cons]
- More expensive ($30-$75 more)
- Light, Flimsy Cord
Both options are great, you just need to decide which one is in your price range and if the
PRO is worth the extra money.