Why bother paying at all? This is basically the same as just walking straight out the store with your goods. A guard won't accept a receipt that says your flat screen tv only cost 49p.
A minor detail here, but British stores don't typically have guards who check receipts (unless you set the alarms off by having a tag left on an item by mistake/shoplifting).
Funnily enough if you buy Tesco's electrical goods online and pick up at store you don't get a paper receipt. The security guard (through lack of training) wasn't keen on letting me out without one.
Also, with the possible exception of membership-based stores like Costco, the "guards" at the front of American stores like Best Buy don't actually have any authority to prevent you from leaving without checking your stuff. Of course, some of them are not correctly instructed on this fact and will break the law and illegally try to obstruct your exit from the store/parking lot anyway.
I've wondered about this for a while, so I looked it up. The Internet (always a trustworthy source, I know...) seems to disagree with you - or at the very most think it's a grey area, leaning towards that they're allowed:
Well I certainly didn't say that they can't ask you to look at your bags. As long as the search is voluntary, they can ask pretty much whatever they like. But you can surely say "no" and then leave. If they physically block you from leaving, they are violating the law in many jurisdictions (they're trying to make a citizen's arrest, which you can't just do without any reason, and refusing to let them look in your bag isn't a reason). If they actually touch you, then you may even have claim of assault. From what I can tell, this has not actually been tested directly, but it is a reasonable expectation of how things would play out, if you took it all the way to court.
On the other hand, the store is also perfectly within their rights to ban you from the premises once you've left. So even if they can't arrest you, they can certainly put a picture up that says "Don't let this guy in the store." It is private property, after all.
The main case mentioned in the thelegality.com article you linked ended with Righi settling with the police so that they dropped the charges in exchange for him giving up the right to sue. Given the balance of resources and power between an individual and a police department, I think that's pretty good evidence that the police department themselves didn't think they were going to win that battle.
The Legal Lad article, on the other hand, seems to just wring its hands about various scenarios without addressing the question everyone cares about: You walk out of a Best Buy, nobody has any reason to believe you stole anything, and when they ask to check your bags, you say "no thanks" and walk out.
I don't know the absolute stats but in 12 years of adulthood I've never had to show a receipt to anyone in the UK and in about 12 weeks of vacations in the US, I've done it several times. So yeah, it might not be a standard thing there, although it does seem to be more of a "thing" people accept.
Ah man, I can't remember all the stores I've been in while on vacation ;-) But yeah, definitely Walmart, and another I remember in particular is Fry's.
The only store of any kind I'm aware of around here that checks receipts every time is Sam's. A lot of places will have "less than friendly" staff by the exit, but explicit security is fairly rare in my experience.
I have a lot of fun with my local Fry's and their "security checks". In reality all I do is briskly walk past, and wish them good morning/day/evening. Most of the time this throws them enough for the moment. They seem to do the math that they're not paid enough to deal with my shit. But the few times it has been raised as an issue, I've always (of course) properly paid for my merchandise.
I know it's a bit immature, but as a result of those minor confrontations, it always gives me the jollies every time I stroll out with just a "Good evening!"
We don't have Fry's on this side of the country. Our Best Buys has toughs right by the door, but they've never stopped me (then again, can't remember the last time I've bought anything particularly expensive from them vs. Amazon...)