Another option - look at the Dell Factory Outlet - if you can be a bit flexible you will find overstock products at a decent saving.
I still make my own, and just had a motherboard failure last weekend - so the whole system had to be stripped down (I used the opportunity to rework some wiring). I purchased a new motherboard and sent the old one back under warranty suggesting they refund the new one. No way - the old one goes back for repair or replacement - in up to four weeks. Imagine a dismantled PC spread across your desk and being unable to use it for up to six weeks (allowing for shipping and fitting times). A whole system with 3-year vendor support would have had no such issues - so there are benefits not building your own.
DO NOT BY FROM DELL UNDER ANY CIRCUMSTANCES. RETAIL OR FACTORY OUTLET.
They have proven to have some of THE WORST customer support in the business, and if Eriktheviking were still on this forum he would have a few very choice words to say about them and his dealings and personal experience with them while working for HP as an electronics engineer. He is not a fan of them at all for a myriad of reasons.
About the only reason Dell are still in business is because they are a well known name whom are usually used for "standard" office machine in thier millions.
If I were you the first thing I would do is identify WHAT exactly you want to use the machine for, because they are not all built the same way; different use, different spec, and then ask for more recommendations - I've been building PC's for myself and other people for 20 years and to my knowledge I have NEVER had a single failure, not one, and I do tell the people I build them for they can call me for any reason any time - it rarely happens. The machine I'm writing this on I built 7 years ago for less than £1500 and it gets hammered, daily use for many hours 5-6 hours a night and more on weekends; 7 years no failure, and I can still play new AAA games on it today after a recent GPU upgrade, the rest is exactly the same as it was.
How long a PC lasts almost always depends on 3 things, sufficient cooling, it not being full of dust and the parts themselves - seems obvious but you would be amazed at the number of people whom think "it's all the same".
Generic machines will ALWAYS have some cost cutting built in and some brands - like Dell - have even been known to put parts in with a limited life span, the revenue that Dell gets from repairs outside of warrenty is HUGE, that's not a good thing.
At the very least Look for a guy on YT called "Linus Tech tips" he really knows his stuff and has videos on just how bad Dell are, and also on how and whom to buy a prebuilt system from or build your own on a budget with components that WILL LAST.
It actually really annoys me how many people get taken in to buying a crap PC by sales blurb and such by salesmen whom know most people don't have a clue (and quite a few salesmen in places like PC World don't know much more either).