the temp gun should do you well enough. i wouldnt worry about a thermometer for the ambient room temperature UNLESS your house fluctuates quite a bit.
something basic should do well, ive never really used a hygrometer and the ones i have used were fairly innacurate. dont even bother with those exoterra hygrometers, terrible.
you can probably get a decent basic indoor/outdoor thermometer/hygrometer/barometer in the garden center at you local hardware store or nursery for a reasonable price