It all depends on your ability
If you only can backlink 100 link one day and you can't make 100 backlink tomorrow , your website can't top rank google , so you need careful
If you do Product Launch to promotion your product and your website is a single site ( 1 site for 1 product), I advice you should build more and more backlinks, it's help your website improve rank and your keywords on top google fast. But if you build backlink for authority site (1 site for more product), 100 backlinks per day will kill your site, it's spam.
Creating huge backlinks to a site wouldn't be effective at all. It will effect your website badly. Try to make genuine backlinks that are coming from high PR sites. It will help you get PR for your web page quickly. Immense backlinks treated as an illegal SEO for a website.
One cannot get genuine 100 back links in a day , Back links can be generated slowly . You can see video over youtube to generate 1000 back links in a min or so but quality of back links is very poor.
You should concentrate on quality rather than quantity because google gives more priority to the quality.Having large number of backlinks with less quality is useless.Even with less number of quality backlinks are enough to get good positions in search results.
Buy online. You can buy backlink online. Go google and search. But I recommend you need build manual, you can build backlink from social networks, forum signature, forum profile, blog, comment luv, magazines...