you might want to have a look at the thread i've start.

Almost same questions as you 

https://bitcointalk.org/index.php?topic=1313023.0

Thanks for all the replies and sharing of knowledge.

I suppose that we will be going for antminer S7 as we feel that it would be better off buying new machines.

Just another note : We had an discussion whether to mine BTC or LTC, and we decided to go for BTC as we did not have the confidence in LTC.

Would love to hear comments from you guys.

EDIT: If we are not mistaken, scrypt miners are not readily available, as most of the companies are hoarding them for own usage. Is that right?

I would like to thank all of you for the experienced and helpful tips.

There's one question that i would require some advice on. I have recently read about BitFury's new chips, and some speculated that it would reach end users by Q2 2016. Should i be waiting, or should i purchase some miners right now?

Also, I am considering of buying alternative PSUs from Ebay. Should i be doing that? Or should i be buying PSUs from the manufacturer of the ASICs?

Some newbie questions too :

1) Should i be buying raspberry pi if i were to go for avalon 6 / antminer s7? I've seen that they have built in controller.
2) Would i require fast internet connection? As there will be alot of miners using the same connection.

We will be placing 10~20 units for a test, before we really go full scale on it.

Thanks for the recommendation.

Why am i considering used miners?

Our ROI is basically Earnings/$$ used to buy hardware. Since our electricity costs are negligible, our only costs is the initial cost for the hardware. Thus, it would be best for us to purchase the lowest $$/TH hardware.

Also, If i'm not wrong, i believe warranty is only for first 3 months, and i've read through this forum that the miners should be working most of the time. So I'm thinking of saving costs and achieving ROI A.S.A.P instead of paying a additional premium for the warranty and being "first owner".

Am I right to think about it this way?

Hi, Have been browsing the forums and learnt alot about bitcoins here.

So, firstly, I would like to thank everyone who shares their experiences in this forum, and also you, who is reading this 

Second, I am thinking of purchasing some miners, Avalon A6 or antminer S7.

Wondering if it would be better to purchasing new ones, or would it be better off purchasing used ones? Also, where should i go searching for used miners?

I have recently read about BitFury's new chips, and some speculated that it would reach end users by Q2 2016. Should i be waiting, or should i purchase some miners right now?

Thirdly, I visited a mining farm of my friend's. I was thinking of installing air conditioning in my farm but he shared with me that he used to do that. but now, he simply suck out the hot air using exhaust fan. Can i ask for some opinions on cooling?

Thanks for all the help!

PS: I'm running on very cheap electricity, almost negligible to our costs.