Daytripper: I wrote this a while back...
1) Distinguish between 141 walk-ups and massage parlour walk-ups (multiple girls, with reception/manager, etc.), a more recent phenomenon competing with both 141s and traditional saunas (which twiceAweek has commented on - he is an expert in that line!), mainly because of ease of access (better locations than 141, simpler to walk into than saunas - hence they charge a lot really for what they deliver by the time you add in the tips). Massage parlour walk-ups that offer additional services are technically illegal, although it seems tolerated by the police at least for a while, as long as they keep a low profile. 141s are labeled "141" in the database, massage parlour walk-ups are "spa".
Here is an example of a "spa"
http://go141.com/en/A43171-TST-S ... l?ref=Search(stype)
The girl photos and presence in the 141 database demonstrate this is not a spa that ladies go to have beauty treatments in!
2) Back to 141 walk-ups. As the name implies it's one girl for one customer in a room (often a very small room from a larger room that that has been subdivided to have more rooms = more rent for the landlord. That's why you'll see addresses like Flat 1, Room D, 3/F, or Flat K6 2/F). 141 walk-ups are legal under HK law (although the landlord position is I feel a bit unclear, but that is not relevant to you), as long as there is only ONE girl in the room. Two or more = brothel = illegal. For a 141 girl to be legal, she has to be a HK resident with the right to work here. Short term 141s are often girls who come across from China for a short visitor visa stay, and hence are operating illegally, and are subject to arrest if discovered by police who occasionally do check ups looking for them. If you are there when that happens, cooperate, nothing much will happen to you (as long as you have ID on you - a requirement in HK)
3) Confusingly there are also girls operating out of individual rooms that are "massage girls". These are 141 girls in effect, but lead with massage services. They may well have experience in massage, and could be working alone after some years in a sauna, and/or they prefer to lead with massage. Some want to offer HJs and maybe BJs and don't want to have sex ("no full package"), although from experience even then they may well offer you the "full package" once you're in the room, for a price uplift, if she likes the look of you. For them the "no full package" label allows them to avoid having sex with some clients without any hassle. They usually offer lots of options on time and add-ons, although some are straightforward with 3 prices massage + HJ, massage + BM (body massage a form of body-to-body) and massage + full set (= full package = sex). Massage girls are labeled "massage" in the database (and are not the same as "spa". Massage girls are legal within the same restrictions as 141s. They tend to be more expensive than 141s, mainly I think because of some concept of offering value through skills in massage (true or not) and time: you can't really offer a 20 or 30 minute massage service with HJ let alone other services... even 45 minutes is tight.
3) Pricing. You've noted that there are a spectrum of prices for 141s. At the lowest you'll see offers for $200 or even $150, but this is usually for a HJ only. One imagines you will be out of there quickly. Next up are $280/300. Then there are quite a lot at $380, $400 then around $500, $600, and even higher. Why the variation? Three factors. First of all. don't expect a beauty at the lowest end. Quite a number of the more expensive girls at $400-500 are not that young, and may not be that attractive, but at the low end, almost all will be old, or ugly, or fat, or all 3! Second, location. You'll pay more in Sheung Wan at Kam Bong than in some dive in Sham Shui Po, because you're paying for the location and rent cost that the girl has to pay. Third time... a lot of the lower cost 141s expect you to be out within 30 minutes, or even less. Some higher cost options will let you stay 45 minutes, even an hour.
How can they be so cheap? Well, turnover. Do the maths, they will pay maybe $7-10,000 per month rent, there will be some additional costs, but if you can say sell 8 sessions a day at $500 for say 20 days a month, plus a few tips... That sounds like a lot of sex? Well it is, so the girl may not be that fresh by 11pm on a Friday! Also it seems the 141 sector is very competitive, hence prices have not gone up that much over recent years, apart from a few buildings, or for a few girls that have very high demand.
To sum up: to a degree you'll get what you pay for, when you pay more you'll probably be in a better building, the girl may well be more attractive, you might get more time. But of course sometimes you'll pay higher $$, but not get much value. Pretty much though the lowest price will get you a service that you might, upon reflection, wish you hadn't bought. It will be hit and miss, so there's value in doing some research, and finding one or a few providers you like at a reasonable price point, and repeat with them, perhaps with a suitable tip. You'll usually get better service.