Are there high DA good business website for guest posting ? Any prediction about how much charges for 1 quality backlinks ?
I think business and industrial based website is suitable for you. According to my experience people are providing two types of guest posting. Use Old Expired Domain or Buy from any auction : Many webmasters buy old expired domains with good DA or buy from any third party and use those domains to add guest posting according to niche market. These types of domains can accept your guest posts for average price like $15.00 per guest post (If you will share unique contents with them). These types of backlinks are average, you can not say them of high quality backlinks. Manual Blog Outreach : This is also types of guest posting but with this service you will get real website from your niche markets. Contact them for add guest post or link in any existing posts. These types of backlinks are of very high quality, but a bit costly, Service provider can charge according to requirement like backlinks from 40+ DA and DR charge will be different and for other condition charge will be different. Average price start from $40 or $50 (Per guest post) for manual blog outreach service according to me. So, its completely depend on you that what you are looking for, choose services according to your budget.
That's awfully specific, why is Aluminium Alloy different from any other site that you need to link build for? FYI: you're now competing with this website for those keywords.
I don't know what article opportunities they offer, but a big player in industrial manufacturers is ThomasNet.com. Some of their members/clients would be interested in your topic, of course.