9to5mac noticed that Apple's 1TB Time Capsule network router/storage device dropped from $500 to $388 on Amazon.com. We also found the 500GB model down to $260 from $300. Apple's Refurb store has similar price drops, although the main Apple online store still has them for their original prices.
As 9to5mac speculates, this could mean an impending Time Capsule refresh. We'll take a stab and say 1TB for $300 and 2TB for $500. Letting the current market guide us, external 1TB drives currently go for $100 to $120, and we've seen 2TB models for as low as $235. A decent N router can be had for less than $150. So that's $250 on the low end for 1TB and $385 on the high end for 2TB for a DIY router/storage combo. Drop the prices for the raw components, throw in the so-called Apple tax and that range could scale nicely with Apple's current price points. Any other guesses?