Here’s my translation

Alan

Þeir sækja fast eftir og segja nú að fé þeirra muni deyja ef þeir fá enga hjálp af honum.
They pursue (press) hard and say now that their cattle will die if they get no help from him.

Hann sagði það af sjálfdáðum orðið "en sagt er mér að Hænsna-Þórir muni hafa hey til sölu."
He said that happened from self-deeds (that they brought it upon themselves?) “but (it) is said to me (ie I am told) that Hænsa (Hen)-Þórir will have hay for sale.”

Þeir svöruðu: "Af honum munum vér eigi fá nema þú farir með oss og
They answered: “We will not get (it) from him unless you go with us and

mun hann þá þegar selja ef þú gengur í vörslu fyrir oss um kaupin."
he will then at-once sell if you become surety (varzla) for us concerning the bargains.”

Hann svarar: "Það má eg gera að fara með yður en það er sannlegt að þeir selji sem til hafa."
He answers: “I may do that, to travel with you but that is probable that they sell who have at-hand.”

Þeir fara snemma um morguninn og var á norðan strykur sá og heldur kaldur. Þórir bóndi var úti staddur í það mund,
They journey early the next morning and gusts-of-wind blew (were) from-the-north (cf vindr var á northan, under norðan, Z1) and (were) rather cold. Farmer Þórir was positioned outside (outside the house) at that time,

sér mennina fara að garði, gengur inn síðan og rekur aftur hurð og lætur fyrir loku, fer til dagverðar.
sees the-men (people) go to (the) yard, goes inside after-that and flings the door to (lit: drives back (the) door) before (?) (the) bolt, goes (present tense) to breakfast.

Nú er drepið á dyr.
Now there is a knock on the door (lit: (it) is knocked on (the) door).

Sveinninn Helgi tekur til orða: "Gakktu út fóstri minn því að menn munu vilja hitta þig."
The-boy Helgi takes to words (starts speaking): “Go-you out my foster-father because men (people) will want to meet you.”

Þórir kveðst mundu matast fyrst en sveinninn hleypur undan borðum og gengur til hurðar og heilsar þeim vel er komnir voru.
Þórir declares-of-himself (that he) would take a meal (ie have his breakfast) first but (and) the boy runs away from (the) table and goes to (the) door and great well those who were (had) come.

Blund-Ketill spurði hvort Þórir væri heima. Hann sagði svo væri.
Blund (Dozy)-Ketull asked whether Þórir was at-home. He said (it) was so.

"Bið þú hann útgöngu," sagði hann.
“Ask (you) him for a going-out (ie to come outside),” he said.

Sveinninn gekk inn og sagði að Blund-Ketill var kominn úti og vildi hitta hann.
The-boy went inside and said that Blund (Dozy)-Ketill was (had) come outside and wanted to meet (see) him.

Þórir svaraði: "Af hverju mun Blund-Ketill draga nasirnar? Kynlegt ef hann fer að góðu. Ekki erindi á eg við hann."
Þórir answered: “From what will Blund (Dozy)-Ketill be-drawing the-nostrils (sniffing around(?)? (It would be) strange if he journeys from good (intentions). I have no business with him.”

Sveinninn fer og sagði þeim að Þórir vildi eigi út ganga.
The-boy goes and said to them (or that-one, ie him, Blund-Ketill?) that Þórir wanted not to go outside.

"Já," sagði Blund-Ketill, "þá skulum vér inn ganga."
“Yes (OK),” said Blund (Dozy)-Ketill, “then we shall go inside.”

Þeir ganga til stofu og var þeim heilsað en Þórir þagði.
They go to (the) sitting-room and (it) was greeted by them (ie they greeted Þórir) but Þórir was (kept)-silent (þegja)

"Svo er varið," sagði Blund-Ketill, "að vér viljum kaupa hey að þér Þórir."
“(It) is so constituted (see verja Z(2).5),” said Blund (Dozy)-Ketill, “that we want to buy hay from you, Þórir.”

Þórir svarar: "Eigi er mér þitt fé betra en mitt."
Þórir answers: “To me your wealth is not better than mine.” (I´m not sure what this means)

Blund-Ketill mælti: "Ýmist veitir það."
Blund (Dozy)-Ketill said: “That happens now-this-now-that (circumstances can change from time to time?)

Þórir svarar: "Hví ertu í heyþroti, auðigur maður?"
Thorir answers: “Why are you in hay-shortage, rich man?”

Blund-Ketill segir: "Eigi er eg greiðlega í heyþroti og fala eg fyrir landseta mína er þurfa þykjast úrlausna. 
Blund (Dozy)-Ketill says: “I am plainly not in a hay-shortage and I am-demandin for purchase on-behalf-of my tenants who bethink-themselves to be in need of help (release from difficulty).

Vildi eg gjarna fá þeim ef til væri."
I would-want willingly to get (it) for them if (it) existed.”

"Það muntu eiga allra heimilast að veita öðrum þitt en eigi mitt."
“You will have that most of all (at your disposal), to grant to others (that which is) yours but not mine.”