Dealing with Dell

My last four computers have been purchased from Dell. I have always been plagued by my own definition of Moore's Law: something like, that computers will do twice as much, for half the price, within 18 months. I feel that whatever I buy, I will be looking at something better within one month. Either the new contraption will be more powerful for roughly the same expenditure, or what I am buying will go down in price in a short time period. Dell has, in the past, had a 30-day refund policy, in that if you buy something, and they lower the price on it within 30 days of your purchase, they will give it to you at a lower price - but only if you call them on it!! All four of my Dell boxes were purchased in this way. Each has yielded about $100.00 credited to my credit card at about the 28-day mark. I make a note to call them within 28 days of my purchase. Since all of the Dell units was custom-built, I cannot cite a competitor selling the same one for less. Only Dell can compete with Dell in this respect. They have always honored their price guarantee, at least with me. Look for similar deals from similar sellers.