SL1400 is the same original series as the SL1200 but it's the more automated version see here Technics SL-1400. What you really need is a Denon DL-110 cart to make it shine but if you want an amp and speakers as well you'll be lucky to get very far for 150USD.
Best thing to do is look at craigslist, thrift stores, garage sales and your local classified ads for a '70s Reciever from one of the major Japanese brands as these will have a phono pre-amp built in. Pioneer, Technics, Sony etc and Marantz were very good too. While you're at it see if the vendors are selling their '70s speakers. On the whole the Japanese ones you'll probably come accross won't be the best so look for the likes of AR or JBL assuming you are in the US.
Your priority should be to find out what cart is on the Technics and see if it's worth getting a new stylus for it, or otherwise a new cart. The Technics arm of this era is fairly high mass so the cheapest modern cart that can deal with this would be an Audio Technica 95E for 50USD. Once you have this sorted then look for the other stuff.