Taking it from relative would save me the interest rate.
No you cant take a "house" loan from a relative. You can but take gift certificates or loan as a personal loan. Not much tax relief there.
Instead like @
babhishek mentioned take a loan from a nationalized bank for say a lesser duration like 10 years. And prepay it using the money your relatives are giving you. But there is a catch.
You still need to prove to the bank where your relative got that money from and some legal agreement on him lending/gifting you the money.
Option 2. Say if property is of 30Lakhs.
Your relative/other individual is giving you say 5Lakhs.
Then do the registration of the property at the value of 25L. Pay the 5L cash to the seller. (This amounts to paid in black ). And for the remaining amount get the loan done or pay from your pocket. But again there are limitations on how much you can undermine the value of your property.
Option 3: Say your relative is giving you 5Lakhs cash. Get receipts made from some local jeweler saying that you sold your ancestral gold to get that money. Now that money becomes white and you can use it anywhere as long as you declare in your tax return filings.