The EF 50mm f/1.8 is great for low-light, especially for the price and is very sharp when stopped up to around f/2.8. The EF-S 55-250 IS lens also has a great price-to-performance ratio and gives you some extra reach with image stabilization. Those 2 lenses and the kit lens are probably the most cost-effective setup if you're planning to invest in a DSLR system.
But why would someone shooting interiors need such long lenses?
I'd recommend the
Panasonic Lumix LX3.
1. For a point and shoot, the image quality appears to be the best. The Canon G10 is also good, but not at high ISO. The LX3 is good in this regard.
2. It's pocket-sized.
3. You can shoot wide-angle equivalent to
24 mm (which is wide
). It's like buying one of the DSLRs recommended above and shooting with a 15 or 16 mm lens attached, and those lenses cost a lot.
4. At 24 mm, the lens has an aperture (i.e. lens "hole") of
f/2!!!!
You CAN'T get that at such a wide angle from any of the lenses recommended above, no matter how much you pay. This lens would allow you to shoot under much lower light conditions handheld (if you need to).
5. At wide angles, many wide angle lenses shoot straight lines that
look like THIS, which is called "barrel distortion". That's a bit of an exaggeration, but you get the idea. Straight lines at the top, bottom, left, and right edges will look really bad. This is HORRIBLE for what you want to do, since there are so many straight lines in a room. At its widest angle, the lens of the LX3 has less barrel distortion than what you get from the large majority of the wide-angle DSLR lenses.
6. The small sensor means the lenses can be VERY short, which results in a very large depth of field (DOF). In English, what this means is that issues like
THIS won't happen, regardless of the lens aperture you use. Everything in your photograph will look sharp.
7.
It costs $429 at B&H. This is near your $400 budget.
Buy a Panasonic LX3 and a Manfrotto Modo tripod, and you'll have a very lightweight, portable kit and take photos as good, and with less distortion than using most of these DSLRs + expensive lens. The alternative is to buy a DSLR and a $400-600 (US dollar) lens, and correct for barrel distortion using Photoshop. They're both over your budget.