Regarding land purchase

There occured agreement between me and seller verbally and also on paper,i given token money in the form of 50,000/-Rs. Cheque ,he given me notes on simple paper ,(regarding cheque received of Rs.50000/- for purchasing land (of servey no.XYZ) and for rate 1400/sq feet rate.)He not ready to make any visar patra or notary. After few days seller demanded me 10 lakh rupees cash without any deal, i directly told him ,remaining amount will give at the time of registration.now he denying agreement and not ready to to sell land, as i not given him rs.10 lakh on his demand .He also not withdrawn cheque ammount. When i given notice through Adv.,he denied any agreement by telling lie with me through answer of his notice. Still i want to purchase land , i have deal notes on simple paper with his sign,stamp of shop.Also he given me old xerox papers of land. My Adv.advised to file civil suit case in court ,which is much expensive, also another adviser advised me that ,on simple paper agreement ,we can not compel seller to sell his property, there needs agreement papers(Visar/Notery/Affidavit).Its my just question ,is such a written commitment with seller sigh,stamp has no any value in the court ? is this not an agreement?? and not valid to purchase land ?? Can any procedure to complete this deal without much loss, please suggest. Thanks.